Combining narrowband applications with broadband transport

ABSTRACT

The combination of narrowband applications with broadband transport may be enabled with a tri-level nodal communications architecture including multiple call control nodes, multiple connection control nodes and one or more intermediates node for interworking between the call control nodes and connection control nodes, in which the intermediate node(s) are controlled by all of the call control nodes. In certain embodiment(s), the identity of the call control node is transmitted to the intermediate node with each message to differentiate between the multiple call control nodes. In addition, each resource (e.g., port) managed by the intermediate node has a call control node identity associated therewith. In further embodiments, a logical port is used to support connections between call control nodes sharing the same intermediate node. The logical port represents a logical E 1  path between the two call control nodes.

CROSS-REFERENCES TO RELATED APPLICATIONS

This U.S. Nonprovisional application for Patent is aContinuation-in-Part of U.S. Nonprovisional application for patent Ser.No. 09/764,953, which was filed on Jan. 17, 2001, which is aContinuation-in-Part of U.S. Nonprovisional application for patent Ser.No. 09/353,135, which was filed on Jul. 14, 1999. U.S. Nonprovisionalapplications for patent Ser. No. 09/764,953 and Ser. No. 09/353,135 arealso hereby incorporated by reference in their entirety herein.

BACKGROUND OF THE INVENTION

This U.S. Nonprovisional application for Patent is further related bysubject matter to U.S. Nonprovisional applictions for patent Ser. No.09/764,622, filed Jan. 17, 2001, Ser. No. 09/765,119, filed Jan. 17,2001, Ser. No. 09/764,960, filed Jan. 17, 2001 and Ser. No. 09/866,135,filed May 25, 2001. These U.S. Nonprovisional applications for patentSer. Nos. 09/764,622, 09/765,119, 09/764,960 and Ser. No. 09/866,135 arehereby incorporated by reference in their entirety herein.

1. Technical Field of the Invention

The present invention relates in general to the field of communications,and in particular, by way of example but not limitation, to usingbroadband transport for narrowband telephony and data communications.

2. Description of Related Art

The increasing interest for high band services such as multimediaapplications, video on demand, video telephone, and teleconferencing hasmotivated development of the Broadband Integrated Service DigitalNetwork (B-ISDN). B-ISDN is based on a technology known as AsynchronousTransfer Mode (ATM) and offers considerable extension oftelecommunications capabilities.

ATM is a packet-oriented transfer mode which uses asynchronous timedivision multiplexing techniques. The packets are called cells andtraditionally have a fixed size. A standard ATM cell comprises 53octets, five of which form a header and 48 of which constitute a“payload” or information portion of the cell. The header of the ATM cellincludes two quantities that are used to identify a connection in an ATMnetwork over which the cell is to travel. These two quantities includethe Virtual Path Identifier (VPI) and the Virtual Channel Identifier(VCI). In general, a virtual path is a principal path defined betweentwo switching nodes of the network; a virtual channel is one specificconnection on the respective principal path.

At its termination points, an ATM network is connected to terminalequipment, e.g., ATM network users. In between ATM network terminationpoints, there are typically multiple switching nodes. The switchingnodes have ports which are connected together by physical transmissionpaths or links. Thus, in traveling from an originating terminalequipment to a destination terminal equipment, ATM cells forming amessage may travel through several switching nodes and the portsthereof.

Of the multiple ports of a given switching node, each may be connectedvia a link circuit and a link to another node. The link circuit performspackaging of the cells according to the particular protocol in use onthe link. A cell that is incoming to a switching node may enter theswitching node at a first port and exit from a second port via a linkcircuit onto a link connected to another node. Each link can carry cellsfor multiple connections, with each connection being, e.g., atransmission between a calling subscriber or party and a calledsubscriber or party.

The switching nodes each typically have several functional parts, aprimary of which is a switch core. The switch core essentially functionslike a cross-connect between ports of the switch. Paths internal to theswitch core are selectively controlled so that particular ports of theswitch are connected together to allow a message to travel from aningress side/port of the switch to an egress side/port of the switch.The message can therefore ultimately travel from the originatingterminal equipment to the destination terminal equipment.

While ATM, because of the high speed and bandwidth that it offers, isenvisioned as the transport mechanism for more advanced services such asB-ISDN, it nevertheless must be recognized that the current narrowbandnetworks (e.g., Public Switched Telephone Networks (PSTN), ISDN, etc.)will remain in use (at least in part) for quite some time. It has takendecades for the present voice switched telephony networks (e.g., PSTN,ISDN, etc.) to reach their present advanced functionalities. While ATMnetworks are being built, the ATM networks will likely not easilyacquire all the functionalities of advanced voice communication.Therefore, at least initially, ATM networks/nodes will in some instancesbe added to parts or will replace parts of circuit switched telephonynetworks. In such instances, ATM will be used for transport andswitching. ATM can actually be used as a single transport and switchingmechanism for multiple other networks, including multiple otherdifferent types of networks. For example, a single ATM network can beused to transport and switch communications from mobile networks (e.g.,Public Land Mobile Networks (PLMNs)), Internet protocol (IP)-basednetworks (e.g., the Internet), etc., as well as landline networks suchas PSTNs and ISDNs.

U.S. Pat. Nos. 5,568,475 and 5,483,527 to Doshi et al., for example,incorporate ATM switches for routing telephony voice signals betweenSynchronous Transfer Mode (STM) nodes. The ATM switches use a signalingsystem No. 7 (SS#7) network to establish a virtual connection, ratherthan a circuit switched connection, as would be the case in a pure STMnetwork. The signaling system No. 7 (SS#7) network of U.S. Pat. Nos.5,568,475 and 5,483,527 includes signal transfer points (STPs) that areconnected by special physical links to each of the ATM switch nodes. Forcall setup, for example, signaling messages are relayed through thesignaling system No. 7 (SS#7) network. In such relaying, a non-ATM STPreceives the signaling message and advises its associated ATM node ofthe call setup. The associated ATM node may then identify idle resourcesto be used for forwarding voice signals to the next ATM node once thecall has been setup, and it may prepare its own signaling message to beused in the relay. The signaling message for the relay that is preparedby the ATM node is returned to its associated STP, which forwards thesignaling message via the signaling system No. 7 (SS#7) network toanother STP associated with the next ATM node. Such relaying continuesuntil the signaling message reaches an STP of an STM local exchangecarrier (LEC). Once the call has been set up, the ensuing speech (orvoice-band data) is transported via the ATM nodes. STM/ATM terminaladapters are situated between the STM network and the ATM network forpacking samples of voice signals as received from the STM network intoATM cells for application to the ATM network, and for unpacking ATM cellpayloads to obtain voice signals for application to the STM network fromthe ATM network. The incorporation of ATM into an STM network in theparticular manner as described above thus involves a non-ATM signalingnetwork alongside the ATM nodes. Furthermore, each STP node associatedwith an ATM node performs only call control functions in the network ofDoshi et al. Otherwise and in general, call control and connectioncontrol is traditionally combined in conventional communication nodes.

With reference now to FIG. 1A, a conventional unified communicationsnode is illustrated at 100. The conventional unified communications node100 may represent any general purpose switching node in atelecommunications network such as a PSTN. Within the conventionalcommunications node 100, the call control 105 functions and theconnection control 110 functions are united. The call control 105 andthe connection control 110 functions together encompass the entire seven(7) layers of the Open System Interconnection (OSI) protocol. Theseseven (7) layers are denoted as the physical, data link, network,transport, session, presentation, and application layers. Accordingly,the conventional communications node 100 may perform all functionsrelated to both switching intelligence and switching fabric.Conventional communication nodes 100 are not, however, capable ofhandling the interworking between (i) narrowband telephony and datacommunications and (ii) broadband communications using faster and higherbandwidth networks, such as ATM networks.

With reference now to FIG. 1B, a conventional approach to separatingfunctions of the conventional unified communications node of FIG. 1A isillustrated generally at 150. Conventional approaches attempt to meetthe stringent demands of interworking narrowband telephony and datacommunications with broadband networks using ATM by separating controlfunctions. Specifically, call control 155 functions are separated fromconnection control 160 functions. The call control 155 functions arethereby made independent of any particular set of connection control 160functions. This separation is typically accomplished by utilizing aconventional communications node (such as the conventionalcommunications node 100 of FIG. 1A) that is stripped of its switchingintelligence, leaving only the connection control 160. In effect, aconventional communications node 100 is modified by removing orrendering inoperative the call control 105 functions, thus leaving onlythe connection control 110 functions. This modified conventionalcommunications node is substituted as the connection control 160 part.The call control 155 part, on the other hand, is typically designed andcreated without relying on traditional telecommunications hardware orsoftware.

With reference now to FIG. 2, an existing scheme for utilizing abroadband network in conjunction with nodes corresponding to separatedfunctions of a conventional unified communications node is illustratedgenerally at 200. Switching intelligence 205A,205B parts are connectedto switching fabric 210A,210B parts. The switching fabric 210A,210Bparts are connected to the ATM network 215, and they effect requiredemulation and cell packing for interworking a narrowband network (notshown) with the ATM network 215. The switching intelligence 205A,205Bparts are usually realized with a UNIX-based server. The switchingintelligence 205A,205B parts are intended to provide the advancedcalling services and features (e.g., those traditionally provided by theIntelligence Network (IN)). The switching intelligence 205A,205B partsdo not include any switching fabric resources, so they must rely on theswitching fabric 210A,210B parts for these resources.

Because the switching intelligence 205A,205B parts do not have any oftheir own switching fabric resources, they are not directly connected toany transport mechanisms, nor do they include the requisite interface(s)for doing so. Incoming calls are therefore received at a switchingfabric 210 part and managed by the associated switching intelligence 205part. When an incoming call is received at a switching fabric 210 part,call signaling information is sent to the switching intelligence 205part. The switching intelligence 205 part performs the appropriate callcontrol functions and sends instructions (e.g., in the form of callsignaling information) to the switching fabric 210 part. The switchingfabric 210 part follows the instructions by making the appropriateconnections (e.g., to/through the ATM network 215, to/through anarrowband network (not shown), etc.) for forwarding the call datainformation for the incoming call. As such, no call data information is(or can be) sent to the switching intelligence 205 part, including fromthe switching fabric 210 part.

Furthermore, while UNIX-based servers, which realize the switchingintelligence 205 parts, may be designed to operate at high speeds, theysuffer from a number of deficiencies. First, significant research,design, and testing is required to produce appropriate software code torun the UNIX-based servers as switching intelligence 205 parts. Existingcircuit-switched voice telephony networks include many advanced featuresthat require many lines of code that have been gradually developed,tested, and implemented over many years. Duplicating the diverse numberand types of features while maintaining the required level ofreliability and service using newly written code on a UNIX server is notonly a daunting task, but it is also virtually impossible to achievequickly. Second, it is extraordinarily difficult to migrate graduallyfrom traditional network architectures (e.g., those using theconventional unified communications node 100 of FIG. 1A) to nextgeneration networks that rely on broadband transport mechanisms whendeploying nodes with only the switching intelligence 205 part. Systemoperators are essentially forced to simultaneously replace wholeportions of their networks in large chunks. The consequential largecapital expenditures are naturally undesirable to system operators.

SUMMARY OF THE INVENTION

The deficiencies of the prior art are overcome by the methods, systems,and arrangements of the present invention. For example, as heretoforeunrecognized, it would be beneficial to re-use and/or extend the life ofexisting/legacy switches when combining narrowband networks withbroadband transport mechanisms. In fact, it would be beneficial toutilize existing switches to enable a gradual migration from narrowbandnetworks to broadband transport mechanisms via the implementation ofhybrid switches.

The present invention is directed to a tri-level nodal communicationsarchitecture including multiple call control nodes, multiple connectioncontrol nodes and one or more intermediates node for interworkingbetween the call control nodes and connection control nodes, in whichthe intermediate node(s) are controlled by all of the call controlnodes. Each of the call control nodes includes both switchingintelligence and narrowband switching fabric, and each of the connectioncontrol nodes includes broadband switching fabric.

In certain embodiment(s), the identity of the call control node istransmitted to the intermediate node with each message to differentiatebetween the multiple call control nodes. In addition, each resource(e.g., port) managed by the intermediate node has a call control nodeidentity associated therewith. In further embodiments, a logical port isused to support connections between call control nodes sharing the sameintermediate node. The logical port represents a logical E1 path betweenthe two call control nodes.

Advantageously, using multiple call control nodes provides additionalcall handling capacity and supports greater amounts of IntelligentNetwork (IN) traffic. The above-described and other features of thepresent invention are explained in detail hereinafter with reference tothe illustrative examples shown in the accompanying drawings. Thoseskilled in the art will appreciate that the described embodiments areprovided for purposes of illustration and understanding and thatnumerous equivalent embodiments are contemplated herein.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the methods, systems, and arrangementsof the present invention may be had by reference to the followingdetailed description when taken in conjunction with the accompanyingdrawings wherein:

FIG. 1A illustrates a conventional unified communications node;

FIG. 1B illustrates a conventional approach to separating functions ofthe conventional unified communications node of FIG. 1A;

FIG. 2 illustrates an existing scheme for utilizing a broadband networkin conjunction with nodes corresponding to separated functions of aconventional unified communications node;

FIG. 3 illustrates an exemplary schematic view of a hybrid STM/ATMnetwork according to an embodiment of the invention;

FIG. 3A illustrates an exemplary schematic view of selected portions ofthe hybrid STM/ATM network of FIG. 3, and further showing variousoperational events;

FIG. 3B illustrates an exemplary schematic view of a hybrid STM/ATMnetwork according to another embodiment of the invention;

FIG. 3C illustrates an exemplary schematic view showing a transit hybridnode pair of the invention connected between two local exchange hybridnode pairs of the invention;

FIG. 3D illustrates a diagrammatic view of an exemplary protocol betweentwo elements of the network of the embodiment(s) of the invention thatinclude hybrid node pairs;

FIGS. 3E, 3F, and 3G illustrate diagrammatic views of alternateexemplary protocols between two elements, a first of the networkelements having a hybrid node pair in accordance with embodiment(s) ofthe invention and a second of the network elements being an access nodewith an additional ATM interface having circuit emulation;

FIG. 3H illustrates an exemplary diagrammatic view showing gradualupgrading of a network from a traditional narrowbandSTM-transported-and-switched environment into an environment with ahybrid STM/ATM network in accordance with embodiment(s) of theinvention;

FIG. 3I illustrates an exemplary schematic view showing a multi-switchhybrid node according to yet another embodiment of the invention;

FIG. 4 illustrates another exemplary scheme for utilizing a broadbandnetwork in conjunction with nodes having partially separated functionsin accordance with the present invention;

FIG. 5 illustrates yet another exemplary scheme for utilizing abroadband network in conjunction with nodes having partially separatedfunctions in accordance with the present invention;

FIG. 6 illustrates another exemplary hybrid switch with multiple portsfor switching a connection in accordance with the present invention;

FIG. 7 illustrates a simplified block diagram of an exemplary hybridswitch in accordance with the present invention;

FIG. 8 illustrates exemplary communications and connections betweennodes in another simplified block diagram of an exemplary hybrid switchin accordance with the present invention;

FIG. 9 illustrates an exemplary method in flowchart form forcommunicating between nodes in a hybrid switch in accordance with thepresent invention;

FIGS. 10A–10E illustrate a first set of exemplary traffic scenarios fora hybrid switch in accordance with the present invention;

FIGS. 10F–10K illustrate a second set of exemplary traffic scenarios fora hybrid switch in accordance with the present invention;

FIG. 11 illustrates an exemplary outgoing communication format selectionfor a hybrid switch in accordance with the present invention;

FIG. 12 illustrates exemplary interactions between a hybrid switch andother telecommunications technology in accordance with the presentinvention;

FIG. 13 illustrates an exemplary traffic scenario migration for a hybridswitch in accordance with the present invention;

FIG. 14 illustrates an exemplary method in flowchart form for enabling agradual migration from a primarily narrowband network to a primarilybroadband network in accordance with the present invention;

FIG. 15 illustrates an exemplary tri-level nodal environment inaccordance with the present invention;

FIG. 15A illustrates a first exemplary tri-level nodal environmentalternative in accordance with the present invention;

FIG. 15B illustrates a second exemplary tri-level nodal environmentalternative in accordance with the present invention;

FIG. 15C illustrates an exemplary interworking function in accordancewith the present invention;

FIG. 16 illustrates an exemplary tri-level nodal environmentimplementation in accordance with the present invention;

FIGS. 17A and 17B illustrate two other exemplary tri-level nodalenvironment implementations in accordance with the present invention;

FIGS. 18A and 18B illustrate two exemplary call setups in an exemplarytri-level nodal environment implementation in accordance with thepresent invention;

FIG. 19 illustrates exemplary communication path configuring in anexemplary tri-level nodal network in accordance with the presentinvention;

FIGS. 20A and 20B illustrate exemplary mapping embodiments in anexemplary tri-level nodal environment implementation in accordance withthe present invention;

FIG. 21 illustrates an exemplary tri-level nodal environment withmultiple call control nodes controlling one or more intermediate nodesin accordance with the present invention;

FIG. 22 illustrates exemplary message handling between an intermediatenode and multiple call control nodes in accordance with the presentinvention;

FIGS. 23A and 23B illustrate exemplary mapping embodiments in theexemplary tri-level nodal environment of FIG. 21 in accordance with thepresent invention;

FIG. 24 illustrates an exemplary method in flowchart form for mappingbetween address spaces in the tri-level nodal environment of FIG. 21 inaccordance with the present invention;

FIG. 25 illustrates a further exemplary mapping embodiment in theexemplary tri-level nodal environment of FIG. 21 in accordance with thepresent invention;

FIG. 26 illustrates an exemplary connection between call control nodeswithin the tri-level nodal environment of FIG. 21 in accordance with thepresent invention; and

FIG. 27 illustrates an exemplary method in flowchart form forestablishing a connection between call control nodes in the tri-levelnodal environment of FIG. 21 in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

In the following description, for purposes of explanation and notlimitation, specific details are set forth, such as particulararchitectures, interfaces, circuits, information exchanges, logicmodules (implemented in, for example, software, hardware, firmware, somecombination thereof, etc.), techniques, etc. in order to provide athorough understanding of the invention. However, it will be apparent toone of ordinary skill in the art that the present invention may bepracticed in other embodiments that depart from these specific details.In other instances, detailed descriptions of well-known methods,devices, logical code (e.g., hardware, software, firmware, etc.), etc.are omitted so as not to obscure the description of the presentinvention with unnecessary detail. It should be understood that theterms “module” and “logic module” as used herein embrace, subsume, andinclude, inter alia, object oriented programming techniques as well asso-called traditional programming techniques such as, for example,custom-developed applications.

Embodiment(s) of the present invention and advantages thereof are bestunderstood by referring to FIGS. 1A–27 of the drawings, like numeralsbeing used for like and corresponding parts of the various drawings.

In certain embodiments in accordance with the invention (e.g., includingembodiment(s) of the invention of the parent applications), ATM is usedas a transport and switching mechanism in a hybrid STM/ATM network,while the signaling remains normal narrowband signaling. The narrowbandsignaling may be transported on permanent paths over ATM connections(e.g., permanent virtual connections (PVCs)), and the narrowband speechchannels may be transported on ATM and switched on a “per call basis”(e.g., on-demand) through an ATM switch (e.g., a switched virtualconnection (SVC)).

The hybrid STM/ATM network has an access node which services narrowbandterminals and which generates a signaling message in connection withcall setup. A translator formats the first signaling message into ATMcells so that the first signaling message can be routed through an ATMswitch to a circuit switched (e.g., STM) node. The circuit switched node(e.g., PSTN/ISDN) sets up a physical connection for the call andgenerates a further signaling message for the call, the furthersignaling message pertaining to the physical connection. The ATM switchroutes an ATM-cell-formatted version of the further signaling message toanother ATM switch over an ATM physical interface. Thus, the ATM switchswitches both narrowband traffic and signaling for the call over the ATMphysical interface. The ATM physical interface thus carries anATM-cell-formatted version of the further signaling message amidst ATMtraffic cells.

In view of the fact that the circuit switched node and the ATM switchemploy different parameters (e.g., b-channel, etc., for the STM node andVP/VC for the ATM switch), in one embodiment the STM node obtains globalposition numbers (GPN) for use in setting a path for the furthersignaling message through the ATM switch. In this regard, at the circuitswitched node a translation is made from STM to GPN using an STM/GPNtranslation table; at the ATM node a translation is made from GPN toVP/VC/port using a GPN/ATM translation table.

The ATM-cell-formatted version of the further signaling message istransported over the ATM physical link and ultimately reaches adestination access node which serves a destination terminal. Adestination translator unpacks ATM cells carrying the ATM-cell-formattedversion of the further signaling message to obtain the STM signalinginformation for use by the destination access node. The translators maybe situated at the access node, for example. In illustratedembodiment(s), the ATM switches are situated at nodes distinct from thePSTN/ISDN nodes, but such need not be the case in other embodiment(s).The signaling messages can be in accordance with the signaling systemno. 7 (SS#7) convention, and the further signaling message can be one ofan ISUP or a TUP message, for example.

Referring now to FIG. 3, an exemplary hybrid STM/ATM network 320according to an embodiment of the invention is illustrated. Narrowbandterminal devices communicate with hybrid STM/ATM network 320 throughaccess nodes, such as access node 322 _(O) and access node 322 _(D). Forexample, FIG. 3 shows terminals 324 _(O) connected to access node 322_(O), particularly ISDN terminal 324 _(O-I) and PSTN terminal 324 _(P).Similarly, access node 322 _(D) has access terminals 324 _(D) connectedthereto, namely ISDN terminal 324 _(D-I) and PSTN terminal 324 _(D-P).Of course, a differing (and most likely greater) number of terminals canbe connected to each access node 322, but for simplicity only two suchterminals are shown for exemplary purposes in FIG. 3. It should be notedthat, as used herein, the term “access node” is not limited to a simplenode used merely for connecting subscriber lines, for it may encompassother nodes such as a local exchange (LE) node, for example.

The hybrid STM/ATM network 320 of FIG. 3 comprises one or more STMnodes, also known as PSTN/ISDN nodes 330. While only two such PSTN/ISDNnodes 330 ₁, and 330 ₂ are shown in FIG. 3 for sake of illustration, itshould be understood that the invention is not limited to only two suchnodes. The structure and operation of conventional PSTN/ISDN nodes 330are well known; such as those typified by utilization of Ericsson AXEswitches, for example. Therefore, only selected pertinent portions ofconventional PSTN/ISDN nodes 330 are described herein with reference toPSTN/ISDN node 330 ₁. For example, PSTN/ISDN node 330 ₁, hasprocessor(s) 332 which execute, e.g., node application softwareincluding switch and resource control software 333. Such software isused to control STM circuit switch 335 as well as signaling terminals337 which comprise PSTN/ISDN node 330 ₁. Other details of the structureand operation of a conventional PSTN/ISDN node are understood, forexample, from U.S. patent application Ser. No. 08/601,964 for“Telecommunications Switching Exchange”, which is hereby incorporated byreference in its entirety herein.

The STM/ATM network 320 of certain embodiment(s) of the invention isconsidered a hybrid network in view of the fact that ATM nodes 340 arealso included therein. As explained hereinafter, the ATM nodes 340 areused not only to route narrowband traffic between access nodes 322, butalso for transport of signaling in ATM cells over an ATM physicalinterface. In the illustrated example, the ATM network aspect includestwo exemplary ATM nodes, particularly ATM node 340 ₁ and ATM node 340 ₂,which are connected by ATM physical interface or link 341. Again, itshould be understood that the ATM component can (and typically does)comprise a greater number of ATM nodes, with the nodes being connectedby ATM physical links.

In hybrid network 320, a PSTN/ISDN node 330 and a ATM node 340 can bepaired together in the manner illustrated in FIG. 3. With such a pair,the PSTN/ISDN node 330 and ATM node 340 are collectively referred to ashybrid node pair 330/340. The network 320 of certain embodiment(s) ofthe invention thus can comprise any number of hybrid node pairs 330/340.An ATM node such as ATM node 340 takes on differing configurations, butcommonly has a main processor 342 or the like which executes applicationsoftware including switch and resource control software as generallydepicted by 343 in FIG. 3. The heart of an ATM node is usually the ATMswitch core or switch fabric, which for the illustrated embodiment isshown as ATM cell switch 345 in FIG. 3. Further information regarding anexemplary ATM switch is provided by U.S. patent application Ser. No.08/188,101, entitled “Asynchronous Transfer Mode Switch”, filed Nov. 9,1998, which is hereby incorporated by reference in its entirety herein.ATM cell switch 345 has plural ingress ports and plural egress ports,with at least some of such ports having a device board attached thereto.

Each device board at ATM node 340 can have one or more differentfunctions performed thereby or one or more different devices mountedthereon. For example, one of the device boards attached to a port of ATMcell switch 345 can, in one embodiment, have the main processor 342mounted thereon. Other device boards may have other processors, known as“board processors”. Some device boards serve as extension terminals(ETs) 346 which may be used to connect the ATM node to other nodes. Forexample, the ATM physical link 341 shown in FIG. 3 has a first endconnected to an extension terminal ET 346 ₁, of ATM node 340 ₁, while asecond end of ATM physical link 341 is connected to an unillustratedextension terminal ET of ATM node 340 ₂. The device boards connected toATM cell switch 345 of ATM node 340 are not specifically illustrated indetail in FIG. 3, but the structure and operation of such device boardsis understood with reference to (for example) the following UnitedStates Patent Applications, all of which are hereby incorporated byreference in their entirety herein: U.S. patent application Ser. No.08/893,507 for “Augmentation of ATM Cell With Buffering Data”; U.S.patent application Ser. No. 08/893,677 for “Buffering of Point-to-Pointand/or Point-to-Multipoint ATM Cells”; U.S. patent application Ser. No.08/893,479 for “VPNC Look-Up Function”; U.S. patent application Ser. No.09/188,097 for “Centralized Queuing For ATM Node”, filed Nov. 9, 1998.

As explained hereinafter, signaling (e.g., for call setup) is routedfrom an access node 322 through an ATM node 340 to an appropriate one ofthe PSTN/ISDN nodes 330. Such being the case, a circuit emulation ortranslator 350 is provided for each access node 322 which communicateswith an ATM node 340. The translators 350 serve, e.g., to encapsulatesignaling information from the access node 322 into ATM cells forsignaling directed toward an ATM node 340, and conversely unpack ATMpayloads received from an ATM node 340 to extract signaling informationfor use by the access node 322. In this particular illustratedembodiment, the translators 350 are preferably provided at or proximateto their associated access nodes 322. That is, translator 350 _(O) maybe situated at or included in access node 322 _(O); translator 350 _(D)may be situated at or included in access node 322 _(D). A pair ofphysical links, shown as links 351, are provided for connecting eachaccess node 322 to a corresponding one of the ATM nodes 340.

ATM node 340 is connected to a PSTN/ISDN node 330 by a physical link360. With reference to ATM node 340 ₁, for example, a pair ofswitch-to-switch links 360 is employed to connect ATM cell switch 345(through its circuit emulation board 370) to STM circuit switch 335 ofPSTN/ISDN node 330, for the carrying of signaling messages. One of thelinks in pair 360 carries messages from ATM cell switch 345 (aftertranslation at circuit emulation board 370) to STM circuit switch 335;the other link of the pair 360 carries messages in the reversedirection.

In the illustrated embodiment, a dedicated VPI, VCI internal to ATM cellswitch 345 is used for signaling. Thus, with reference to ATM node 340₁, for example, link 351 _(O) is connected to extension terminal (ET)346 ₂, which in turn is connected to a first pair of dedicated ports ofATM cell switch 345. Signaling messages received at ATM node 340 ₁ whichare destined to PSTN/ISDN node 330 ₁, are routed on the dedicatedinternal VPI/VCI to a port of ATM cell switch 345 which ultimatelyconnects (via circuit emulator 370) to switch-to-switch links 360.However, since the signaling routed through ATM cell switch 345 isencapsulated in ATM cells, a translation to the STM signaling must beperformed prior to transmitting the signaling information onswitch-to-switch links 360. For this reason, a device board connected toswitch-to-switch links 360 has the circuit emulation (CE) or translator370 mounted thereon.

The circuit emulation (CE) or translator 370 serves to unpack signalinginformation which is destined to PSTN/ISDN node 330, but contained inATM cells, so that the signaling information can be extracted from theATM cells prior to application on switch-to-switch links 360.Conversely, signaling information received from PSTN/ISDN node 330 ₁ onswitch-to-switch links 360 at translator 370 is encapsulated into ATMcells for routing through ATM node 340 ₁. From FIG. 3 it can also beseen that a plurality of interfaces 300 a–300 f are utilized in thehybrid STM/ATM network 320 of certain embodiment(s) of the invention.These interfaces are described below, primarily with reference to theexemplary nodes (e.g., PSTN/ISDN node 330 ₁ and ATM node 340 ₁).

Interface 300 a is a logical interface which exists between processor(s)332 of PSTN/ISDN node 330 ₁, and main processor(s) 342 of ATM node 340₁. Interface 300 a enables PSTN/ISDN node 330 to control the ATM node340 connected thereto. That is, with the signaling carried by interface300 a, PSTN/ISDN node 330 ₁ can order physical connections which are tobe set up in ATM node 340 ₁. Interface 300 a can be a proprietaryinterface or an open interface (such as a General Switch ManagementProtocol (GSMP) interface [see Request For Comments (RFC) 1987]).Logical interface 300 a can be carried on any physical interface, suchas interface 360 described below. Alternatively, interface 300 a can becarried by a separate link (e.g., between processors 332 and 342), orcarried on top of IP/Ethernet links.

Interface 300 b is the signaling between the PSTN/ISDN nodes 330 and theaccess node 322 connected thereto. Interface 300 b is carried on one ormore semipermanent connections through the STM circuit switch 335;through the interworking unit with circuit emulation 370 into ATM cellswitch 345; and over permanent virtual connections to access node 322(particularly to translator 350 in access node 322, where it is emulatedback and terminated). As mentioned above, translator 350 is employed toencapsulate the narrowband signaling from an access node 322 in ATMcells for use by an ATM node 340, and conversely for unpacking ATM cellswith signaling information for use by an access node 322. Each STMchannel on the user side may have a corresponding VPI/VCI on interface300 b.

Interface 300 c is the non-broadband signaling that is carried throughand between the nodes. Interface 300 c thus carries the normal signalingsystem No. 7 (SS#7) interface (e.g., TUP or ISUP) which is transparentlycarried in ATM-cell-formatted versions of signaling messages over ATMphysical link 341. In PSTN/ISDN node 330, the signaling terminals 337are used for common channel signaling. In at least one embodiment,signaling terminals 337 can be pooled devices situated at STM circuitswitch 335. Alternatively, the signaling terminals 337 can be connecteddirectly to the interfaces between the STM and ATM switches.

Interface 300 d is the physical interface provided by switch-to-switchlink 360. Interface 300 d can be used to carry speech for a call to andfrom an STM network, and also to carry the signaling of interface 300 band interface 300 c as described herein. In addition, interface 300 dcan also be used to link-in special equipment that is to be connected toa normal circuit switch (e.g., conference equipment, answering machines,etc.). Interface 300 d can be realized by any standard physical media,such as E1, for example; it being understood that STM-1 or similarspeeds may be suitable. The physical interface 300 d can also carry thevoice data for a conversation between any of the terminals shown in FIG.3 and an unillustrated terminal connected to the circuit switchednetwork, in which situation the hybrid node pair 330/340 acts as agateway.

Interface 300 e is the ATM physical link 341 to other ATM nodes. Anystandard link for ATM may be employed for interface 300 e. A dedicatedVP/VC is employed to transparently transfer the signaling system no. 7(SS#7) signaling between PSTN/ISDN nodes 330 over interface 300 e.Interface 300 f, shown in FIG. 3 as connecting each access node 322 withits terminals, is a typical user-network interface (e.g., ISDN, BA/BPA,PRA/PRI, two-wire PSTN, etc.)

For two traditional circuit switched PSTN/ISDN nodes to communicate withone another using protocols such as ISUP or TUP, it is preferable thatISUP entities in both PSTN/ISDN nodes have coordinated data tables. Inthis regard, each of the two PSTN/ISDN nodes has a table whichtranslates a CIC value onto a same timeslot in a same physical interfaceconnecting the two PSTN/ISDN nodes. Thus, a CIC value (together with apoint code) represents a particular timeslot on a particular physicallink. One specific CIC preferably points out the same time slot in thetables of both PSTN/ISDN nodes. In other words, the data tables of thetwo PSTN/ISDN nodes are preferably coordinated.

The need to coordinate the data tables of PSTN/ISDN node 330 ₁ andPSTN/ISDN node 330 ₂ for ISUP/TUP similarly exists in certainembodiment(s) of the invention. If two hybrid nodes 330 ₁/340 ₁ and 330₂/340 ₂ have a communication channel set up between them, by means of asemipermanent connection carrying SS#7 signaling for example, thetranslation tables 339 in both hybrid nodes are preferably coordinatedfrom the standpoint of using CIC. This typically means that in bothhybrid nodes 330 ₁/340 ₁ and 330 ₂/340 ₂ a certain CIC points at thesame VP and VC (and possibly AAL2 pointer) identifying cells on acertain physical link (e.g., link 341) connecting the two hybrid nodes.Alternatively, the same objective may be accomplished by other suitablemeans such as a cross-connected-ATM switch positioned between the hybridnodes that switches packets and gives the packets the VP and VC valueunderstood by the other node.

Referring now to FIG. 3A, an exemplary structure of hybrid STM/ATMnetwork 320, having omitted therefrom various items including theinterfaces, is illustrated. FIG. 3A also provides an example of signalprocessing for a call originating at terminal 324 _(O-P) for which thecalled party number (destination) is terminal 324 _(D-P). As shown bythe arrow labeled E-1, at event E-1 a SETUP message is sent fromterminal 324 _(O-P) to access node 322 _(O). In the illustratedembodiment, the SETUP message is an IAM message for an ISUP networkinterface, and is for a 30B+D PRA and for VS.x carried on a 64 kb/s bitstream in a circuit switched timeslot.

At the translator 350 _(O) associated with the access node 322 _(O), atevent E-2 the signaling from terminal 324 _(O-P) is converted from STMto ATM by packing the signaling information into ATM cell (s). In thisregard, after the circuit emulation a table is employed to translatefrom a 64 kb/s speech channel from terminal 324 _(O-P) to acorresponding ATM address (VP/VC). The signaling of the SETUP message,now encapsulated in ATM cell(s), is applied to link 351 _(O) andtransmitted to ATM cell switch 345 of ATM node 340 ₁ as indicated byevent E-3. As further indicated by event E-4, the ATM cell(s) containingthe SETUP message signaling is routed through the ATM cell switch 345 inaccordance with a switch internal VP/VC dedicated for STM-originatedsignaling. Upon egress from ATM cell switch 345, the signalinginformation for the SETUP message is retrieved from the ATM cell(s) bytranslator 370 (event E-5), and it is reconverted at translator 370 fromATM to STM format, so that the SETUP message signaling information canbe applied in STM format at event E-6 to switch-to-switch link 360. TheSETUP message, now again in STM format, is routed through STM circuitswitch 335 (as indicated by event E-7) to an appropriate one of thesignaling terminals 337. Upon receipt of the SETUP message signalinginformation at the appropriate signaling terminal 337, the signalinginformation is forwarded to processor(s) 332 of PSTN/ISDN node 330,which engage in STM traffic handling (as indicated by event E-8).

In its traffic handling, the processor 332 of PSTN/ISDN node 330realizes that the incoming side of the call and the outgoing side of thecall have physical connections through an ATM node. In this regard, whenthe access points of the connection were defined (subscriber or networkinterface), a bearer type was associated with the connection and storedin application software. In the present scenario, when the SETUP message(e.g., an IAM message in the case of an ISUP network interface) wasreceived at PSTN/ISDN node 330, the stored bearer type data was checkedin order to determine what switch was on the incoming side to PSTN/ISDNnode 330. Further, the bearer type data stored for the outgoing point(e.g., based on B-Subscriber number) is similarly checked, and if thestored data indicates that both incoming and outgoing sides have an ATMbearer, the PSTN/ISDN node 330 can conclude that ATM node 340 is to beoperated (e.g., utilized). In addition, data received in the SETUPmessage (particularly the B-subscriber number) is analyzed to determinethat the called party (destination) terminal 324 _(D-P) can be reachedby contacting PSTN/ISDN node 330 ₂. The PSTN/ISDN node 330 ₁ realizesthat it has an SS#7 signaling interface 300 c to PSTN/ISDN node 330 ₂,and therefore selects a free CIC (e.g., a CIC not used by any othercall) for use toward PSTN/ISDN node 330 ₂.

If, on the other hand, the stored bearer type data had indicated an STMbearer, both PSTN/ISDN node 330 and ATM node 340 have to be operated.Thus, PSTN/ISDN node 330 and ATM node 340 collectively function as agateway between the STM and ATM worlds. Upon realizing that furthersignaling for the call will be routed through ATM nodes, in theembodiment(s) of the invention shown in FIG. 3 and FIG. 3A, thePSTN/ISDN node 330 ₁ makes reference to an STM/GPN translation table 339maintained by processor(s) 332 (see event E-9). Two translations areperformed using the STM/GPN translation table 339. As a firsttranslation, the information (e.g., b-channel and access information inthe case of ISDN or CIC plus signaling system #7 point codes in the caseof PSTN) contained in the SETUP message is translated to a globalposition number (GPN). As a second translation, the CIC and destinationpoint code for a circuit leading to hybrid node pair 330/340 istranslated to another global position number (GPN).

In connection with the foregoing, the global position number (GPN) is acommon way to identify the connection points, and as such is understoodby the pair of nodes (PSTN/ISDN node 330 and ATM node 340). In otherwords, the GPN is an address, or reference, or system internal pointerknown by both PSTN/ISDN node 330 and ATM node 340, and used to translatebetween port/VP/VC and circuit switch address. Usage of GPN in theembodiment of FIG. 3 and FIG. 3A thereby obviates the sending of realaddresses between PSTN/ISDN node 330 and ATM node 340. Advantageously,GPN can be shorter, meaning that there is less data to send. Fortraditional PSTN, the GPN uniquely corresponds to the 64 kbit voice on atwo-wire line, but for ISDN, the GPN corresponds to a b-channel (whichmay be used by several subscribers).

Then, as event E-10, the PSTN/ISDN node 330 generates an ATM switchcontrol message intended to setup a physical connection in ATM node 340.This message of event E-10 contains the two global position numbers(GPNs) obtained from STM/GPN translation table 339 at event E-9,together with an order for the ATM node 340 to connect the two GPNaddresses in ATM switch fabric 345. The PSTN/ISDN node 330 sends theswitch control message generated at event E-10 to processor 342 of ATMnode 340 over interface 300 a, as shown by event E-11.

Upon reception of the switch control message sent as event E-11 to ATMnode 340 ₁, as indicated by event E-12, main processor 342 consultsGPN/ATM translation table 349 in order to translate the two globalposition numbers (GPNs) contained in the event E-10 switch controlmessage into VP/VC/port information understood by ATM node 340 ₁. Thatis, the two global position numbers (GPNs) are used to obtain VP/VC/portinformation for ultimately reaching both the origination terminal (324_(O-P)) and the destination terminal (324 _(D-P)). Upon successfultranslation of GPN to ATM, and assuming sufficient resources, processor342 of ATM node 340 ₁ sets up a path through ATM Switch 345 and reservesresources on the port (trunk or link 341) for the call from terminal 324_(O-P) to terminal 324 _(D-P). The path set up and resource reservationactivities are accomplished using switch/reservation control 343 and arecollectively illustrated as event E-13 in FIG. 3.

Since PSTN/ISDN node 330 preferably knows whether ATM node 340 ₁ wassuccessful in performing a GPN/ATM translation, a successful translationmessage is sent over interface 300 a as event E-14 from ATM node 340 ₁to PSTN/ISDN node 330 ₁. If the GPN/ATM translation is not successful atATM node 340 ₁, or if there are no available resources at ATM node 340₁, a call rejection message is sent back to the originating terminal.After PSTN/ISDN node 330 receives the confirmatory message of event E-14(that ATM switch 345 has been setup and link reservations made (inaccordance with event E-13)), at event E-15 the PSTN/ISDN node 330 ₁prepares and sends its further signaling message (e.g., ISUP or TUP)toward the PSTN/ISDN node at the other end (e.g., PSTN/ISDN node 330 ₂)This further signaling message is shown as event E-15 in FIG. 3A. Thesignaling of event E-15 (e.g., an ISUP or TUP message) includes amessage transfer part (MTP), and can be sent out on a timeslot (e.g., 64kb/s) which carries the SS#7 signaling.

As the signaling of event E-15 arrives at ATM node 340 ₁, the ATM node340 ₁ prepares its ATM cell-formatted version of the signaling. Inparticular, the translator 370 puts the signaling information of thesignaling of event E-15 into the payload of one or more ATM cells. Forexample, the translator 370 is configured to take the 64 kb/s signalinginformation bit stream and to pack it into ATM cells with a predefinedVP, VC, and a physical port. As also indicated as event E-15, the ATMcell-formatted version of the further signaling message is routedthrough ATM cell switch 345 and onto a link indicated by the VP/VC/portinformation obtained from the translation. In particular, in FIG. 3A theATM cell-formatted version of the further signaling message istransported on ATM physical link 341, as shown by event E-16.

Upon reaching ATM node 340 ₂, the ATM cell-formatted version of thefurther signaling messages obtains a new internal VPI/VCI for the ATMcell switch 345 of ATM node 340 ₂, and is routed (as indicated by eventE-17) through ATM cell switch 345 of ATM node 3402 to a circuit emulator(not explicitly shown) in ATM node 3402, which is analogous to circuitemulator 370 in ATM node 340 ₁. The circuit emulator of ATM node 340 ₂performs the conversion from ATM to STM format in like manner as circuitemulator 370 in ATM node 340 ₁, and then passes the signaling message toPSTN/ISDN node 330 ₂ as event E-18.

In PSTN/ISDN node 330 ₂, the ISUP message is received together with theCIC value (from the message transfer part (MTP)) and the B-subscribernumber (which is included in the ISUP message). As indicated by eventE-19, the second hybrid node 330 ₂/340 ₂ also performs an analysis ofthe B-subscriber number and concludes that the B-subscriber number isassociated with terminal 324 _(D-P), which involves B channels. ThePSTN/ISDN node 330 ₂ then selects a B-channel which can be used to reachterminal 324 _(D-P), or negotiates with the terminal 324 _(D-P) as towhich B-channel to use (depending on the terminal type and protocol typeISDN or PSTN). The PSTN/ISDN node 330 ₂ also signals terminal 324 _(D-P)to activate a ringing signal (as indicated by event E-20). When ananswer is received from terminal 324 _(D-P) (or during or beforereceiving an answer), the PSTN/ISDN node 330 ₂ consults its STM/GPNtranslation table 339 (not explicitly shown) using a CIC value and aB-channel. The PSTN/ISDN node 330 ₂ then operates the ATM switch 345(not explicitly shown) of ATM node 340 ₂ in the same manner as describedfor ATM node 3401, as indicated by event E-21.

Operation of ATM switch 345 of ATM node 340 ₂ allows in-band data (e.g.,voice data) carried in ATM packets to be passed through the ATM switch.Such operation is accomplished in like manner as described previouslyhereinabove (e.g., by consulting a table such as table 339, by sendingan ATM switch control message, by consulting a table such as table 349,and by setting up of a path in the ATM switch). When an ATM switch isoperated as described above, the resulting path through both ATMswitches (carrying in-band information) has to be set up in the same wayat both ends. This implies that encapsulation of in-band information(which is controlled by circuit emulation (e.g., circuit emulation 370))at the two end points of the path is preferably set up in the same way.To minimize delay, AAL2 is preferably utilized by circuit emulation 370for the encapsulation, although other types of protocols may bealternatively used.

As noted hereinabove, a bearer type is associated with a connection andstored in the application software of the PSTN/ISDN node 330. It ispresumed that the PSTN/ISDN node 330 already is able to handletraditional access points (subscriber or network interfaces) connectedto STM circuit switches. In so doing, the PSTN/ISDN node 330 has logicalrepresentations of these existing access points in a static datastructure of the PSTN/ISDN node 330. In accordance with certainembodiment(s) of the invention, the PSTN/ISDN node 330 additionallyhandles access points connected to the ATM switch. In this regard, see(for example) interface 341 of FIG. 3C (hereinafter described). Thus,for certain embodiment(s) of the invention, the PSTN/ISDN node 330 haslogical representations of these additional access points in its staticdata structure. Therefore, the bearer type data may be employed in theprior discussion as a way of distinguishing the logical representationof the additional access points (e.g., ATM-related access points) in thestatic data structure from the logical representation of the traditionalaccess points.

It was also noted hereinabove that encapsulation of in-band informationis preferably set up the same way at both ends. More specifically, asame type of cell filling is preferably employed by two circuitemulation devices that are connected together. For example, if on a linkconnecting two circuit emulation devices an ATM cell is packed with onlyone voice sample by a first of the circuit emulation devices, the secondof the circuit emulation devices preferably packs ATM cells in a similarmanner. Alternatively, another emulation and/or bridging mechanism orscheme may be employed.

In the above regard, filling only part of an ATM cell with informationis a technique for reducing delays, although it may increase overhead.Another way of reducing delay is employment of the AAL2 protocol. Asunderstood by those skilled in the art, AAL2 is a protocol layer on topof ATM, and it allows transport of mini-cells within ATM cells. Usage ofthe smaller AAL2 cells helps address bandwidth and delay problems in theair interface. Certain embodiment(s) of the invention may be utilizedwith AAL2 switching as an alternative to ATM switching. If oneimplements AAL2 in certain embodiment(s) of the invention, the switch345 operates as an AAL2 switch and GPN/ATM translation table 349 in ATMnode 340 preferably also includes an AAL2 pointer. Whenever the ingressand egress point is referenced, it can alternately include an AAL2pointer. Thus, as used herein and in the appended claims, ATMencompasses ATM-related protocols on top of ATM, such as AAL1, AAL2,AAL5, etc. It should also be understood that the term “broadband”, asused herein and in the appended claims, embraces and encompassespacket-switched technologies in general (e.g., IP, VoIP, Frame-relay,ATM, etc.).

Referring now to FIG. 3B, an exemplary hybrid STM/ATM network 320′according to another embodiment of the invention is illustrated. Theembodiment of FIG. 3B primarily differs from the embodiment of FIG. 3 inthat the embodiment of FIG. 3B does not employ global position numbers(GPNs). Rather, the embodiment of FIG. 3B uses an ATM/STM translationtable 339′ in processor 332 of PSTN/ISDN node 330 ₁ instead of anGPN/ATM translation table. In the embodiment of FIG. 3B, the translationtables in the circuit emulation 350 ₀ translate the SETUP message from a64 kb/s speech channel to an ATM address (VP and VC) in a manner similarto that of event E-2 in the embodiment(s) of FIG. 3 and FIG. 3A. Afterrouting of the translated SETUP message through ATM switch 345 ₁, thecircuit emulation 370 translates the SETUP message to the STM format asoccurred at event E-5 of the embodiment(s) of FIG. 3 and FIG. 3A.

The embodiment of FIG. 3B also differs from that of the embodiment(s) ofFIG. 3 and FIG. 3A in that processor 332 of PSTN/ISDN node 330terminates the narrowband signaling by translating a narrowbandreference point (e.g., b-channel if an ISDN connection) to acorresponding ATM address for use by ATM node 340. Thus, for the FIG. 3Bembodiment, the switch control message of event E-11 sends the ATMVP/VC/port information understood by ATM node 340 ₁. Thus, thetranslation of event E-12 of the FIG. 3/FIG. 3A embodiment isunnecessary in the FIG. 3B embodiment. Rather, upon receiving the ATMVP/VC/port information in the switch control message of event E-11, theembodiment of FIG. 3B proceeds to the path set up and resourcereservation operations denoted as event E-13.

The principles as illustrated in the embodiments hereof are alsoapplicable to the carrying of other types of signaling messages in ATMcells. Included among such other types of signaling messages are thosedestined for the originating terminal (e.g., a call completion signalingmessage), in which case some of the events described herein areperformed essentially in reverse order.

Referring now to FIG. 3C, an exemplary illustration of how hybrid nodepairs 330/340 of the invention may be arranged in an exemplary hybridSTM/ATM network 320″ is presented. Network 320″ has three node pairs330/340, including a transit exchange hybrid node pair 330/340 _(TX)between two local exchange hybrid node pairs 330/340 ₁ and 330/340 ₂.FIG. 3C shows provision of a “#7 signaling system” 393, which is alogical system carried in the ATM network on an ATM AAL layer asdescribed above. As an alternative embodiment, the “#7 signaling system”393 may be provided with its own physical network.

Referring now to FIG. 3D, a diagrammatic view of an exemplary protocolusable between two elements of a network in accordance withembodiment(s) of the invention that include hybrid node pairs isillustrated. The ATM node 340 with its ATM switch 345 terminates the ATMand AAL1 (circuit emulation part) layers; the PSTN/ISDN node 330terminates the MTP and ISUP layers.

Referring now to FIGS. 3E, 3F, and 3G, diagrammatic views of alternateexemplary protocols between two elements, a first of the networkelements having a hybrid node pair in accordance with embodiment(s) ofthe invention, and a second of the network elements being an access nodewith an additional ATM interface with circuit emulation is illustrated.In the first network element, the ATM switch 345 terminates the ATM andAAL1 (circuit emulation part) layers, while the layers above areterminated by the PSTN/ISDN node 330. In the second network element, theATM interface and circuit emulation addition to the access nodeterminates the ATM and AAL1 layers, while the layers above areterminated by the connected terminal and the access node part. Theexemplary protocols of FIGS. 3E, 3F, and 3G can be used, for example, onthe interface 300 b.

Referring now to FIG. 3H, an exemplary gradual upgrade of a network froma traditional narrowband STM-transported-and-switched environment intothe environment (e.g., hybrid STM/ATM network 320) of certainembodiment(s) of the invention is illustrated. In FIG. 3H, the circuitemulation equipment (translator) 395 separates the hybrid environmentfrom the pure STM environment. If node B (PSTN/ISDN node 330 _(N+1)) isupgraded with ATM switching and (signaling and traffic) transportaccording to certain embodiment(s) of the invention, the node C(PSTN/ISDN node 330 _(N+2)) is not disturbed if the circuit emulationequipment (translator) 395 is moved in between nodes B and C in themanner illustrated by the dotted-dashed line 396 as shown in FIG. 3H.

Referring now to FIG. 3I, certain embodiment(s) of the invention permitthe possibility of one logical node to include many switches, withswitching logic within the node coordinating the setting up of pathsthrough the switches. This logic also inserts interworking functions(IWFs) between switches (if needed), and makes it possible to useresources independent on which switch they are allocated to. Forexample, the multi-switch node 397 of certain embodiment(s) of theinvention includes the PSTN/ISDN node 330 with its STM switch 335,connected by interface 300 d to ATM node 340 ₇₋₁. Specifically,connection is made through IWF 344 ₇₋₁ to ATM switch 345 ₇₋₁ of ATM node340 ₇₋₁. The ATM switch 345 ₇₋₁ of ATM node 340 ₇₋₁ is connected byinterface 300 e to an ATM network, as well as to ATM node 340 ₇₋₂ andATM node 340 ₇₋₃ included in the multi-switch node 397. The ATM node 340₇₋₂ has a switch 345 ₇₋₂ and an IWF 344 ₇₋₂, through which connectioncan be made with access node 322 ₇₋₁. The ATM node 340 ₇₋₃ has an ATMAAL2 switch 345 ₇₋₃, which connects to ATM nodes 340 ₇₋₁ and 340 ₇₋₂through IWF 344 ₇₋₃ of ATM node 340 ₇₋₃. Access nodes 322 ₇₋₂ and 322₇₋₃ are connected to ATM AAL2 switch 345 ₇₋₃ of ATM node 340 ₇₋₃.

Certain embodiment(s) of the invention advantageously reuse PSTN andISDN software in the PSTN/ISDN nodes 330 in a fairly simple way. Thatis, already-developed narrowband application software residing in thePSTN/ISDN nodes 330 can be utilized, while on-demand ATM connections areused as traffic bearers. The invention thus allows a PSTN/ISDN node suchas PSTN/ISDN node 330 to control the call, which facilitates use ofwell-proven software for various services and functions (e.g.,subscriber services, intelligent network (IN) services, Centrex,Charging Customer Care systems, etc.).

ATM is thus used as a transport and switching mechanism in certainembodiment(s) of the invention, while the signaling remains normalnarrowband signaling. The narrowband signaling is transported onpermanent paths over ATM connections, and the narrowband speech channelsare transported on ATM, and switched on a “per call basis” (e.g.,on-demand) through an ATM switch.

The narrowband application software executed by processor(s) 332 ofPSTN/ISDN nodes 330 thus acts as if operating on its STM circuitswitched transport, when in fact it is actually operating on an ATM cellswitch. It should be understood that the ATM switch may reside in aseparate ATM node or may be integrated in the same node as the STMswitch. On a “per call basis”, the switching logic in the PSTN/ISDNnodes 330 requests the switching mechanism in the ATM nodes 340 to beset up and disconnected through an ATM cell switch.

It should be understood that variations of the foregoing are within thescope of the embodiments of the invention. For example, the circuitemulation 370 is shown (e.g., in FIG. 3) as being provided on a deviceboard of ATM node 340. Alternatively, circuit emulation 370 may belocated elsewhere, such as (for example) on link 360 between PSTN/ISDNnode 330 and ATM node 340, or even included in PSTN/ISDN node 330 (e.g.,at either end of interface 300 d). While various processors, such asprocessors 332 and 342, have been illustrated as single processors, itshould be understood that the functionality of such processors may besituated or distributed in different ways (e.g., distributed overseveral processors to achieve, e.g., scalability in respect toprocessing capacity and reliability), for example.

In the foregoing examples, the SETUP message (received at the STM nodein STM format) is routed through STM circuit switch 335 as indicated bythe event E-8 to signaling terminals 337. It should be understood,however, that depending upon implementation in an PSTN/ISDN node,signaling may take another way to reach a signaling terminal (e.g.,other than through a switch). The invention also describes a system withone STM switch and one ATM switch associated with one another. Thisparticular configuration is advantageous in that resources which takecare of certain kinds of signals (e.g., in-band signals) may be situatedin the STM switch and be used also for the ATM transported calls. Thisis also a way of reusing the installed base, if such exists. Also,certain embodiment(s) of the invention can perform switching on variouslevels, such as the AAL2 level and with mini-cells, which tends toreduce any delay/echo problems.

The invention thus pertains to the telecommunications world and anattempt to introduce ATM to a telecommunications network. The inventionaddresses the situation in which a circuit switched telephony networkpre-exists, and it is to be augmented or partially replaced by partsthat employ ATM for transport and switching. Certain embodiment(s) ofthe invention need not employ broadband signaling, but rather narrowbandsignaling with the bearer part of the call following the signaling tothe same extent as in a traditional narrowband circuit switched network.

As described herein, ATM may be used as a transport and switchingmechanism in a hybrid STM/ATM network, while the signaling remainsnormal narrowband signaling. The narrowband signaling may be transportedon permanent paths over ATM connections, and the narrowband speechchannels may be transported on ATM and switched on a “per call basis”(e.g., on-demand) through an ATM switch. The hybrid STM/ATM network mayinclude an access node that services narrowband terminals and whichgenerates a signaling message in connection with call setup. Atranslator formats the first signaling message into ATM cells so thatthe first signaling message may be routed through an ATM switch to acircuit switched (e.g., STM) node. The circuit switched node (e.g.,PSTN/ISDN) sets up a physical connection for the call and generates afurther signaling message for the call, the further signaling messagepertaining to the physical connection. The ATM switch routes an ATMcell-formatted version of the further signaling message to another ATMswitch over an ATM physical interface. Thus, the ATM switch switchesboth narrowband traffic and signaling for the call over the ATM physicalinterface.

Referring now to FIG. 4, another exemplary scheme for utilizing abroadband network in conjunction with nodes having partially separatedfunctions in accordance with the present invention is illustratedgenerally at 400. The nodes 405A,405B are connected to the nodes410A,410B. The nodes 405A,405B each include both call control functionsand connection control functions. In effect, each of the nodes 405A,405B(e.g., which may correspond to, for example, PSTN/ISDN nodes 330 of theembodiment(s) of FIG. 3 et seq.) include both switching intelligence(e.g., which may correspond to, for example, one or more of processor(s)332, switch and resource control software 333, signaling terminals 337,and STM/GPN translation table 339 of the embodiment(s) of FIG. 3 etseq.) and switching fabric (e.g., which may correspond to, for example,an STM circuit switch 335 of the embodiment(s) of FIG. 3 et seq.). Whilethe nodes 410A,410B include connection control functions, they rely onthe call control functions of the nodes 405A,405B to which they arerespectively connected. In effect, each of the nodes 410A,410B (e.g.,which may correspond to, for example, ATM nodes 340 of the embodiment(s)of FIG. 3 et seq.) include switching fabric (e.g., which may correspondto, for example, an ATM cell switch 345 of the embodiment(s) of FIG. 3et seq.). The nodes 410A,410B, which are also connected to an ATMnetwork 215, effect required emulation and cell packing for interworkinga narrowband network (not shown) with the ATM network 215.

Generally, and in certain embodiment(s), call control involves features,functions, responsibilities, etc. pertaining to one or more of thefollowing: routing a call; signaling between narrowband nodes; providingsubscriber services; implementing charging; determining the connectionand/or activation of tone senders, answering machines (e.g., voicemail), echo cancelers, and other types of telephony resources and/orequipment; ascertaining the desirability and/or necessity of utilizingan IN service; etc. Connection control, on the other hand, involvesfeatures, functions, responsibilities, etc. pertaining to settingup/establishing a connection between two (or among/across multiple)physical points within a switch and/or over a network responsive to callcontrol, for example. The connection control, to effectuate such aconnection, may rely on some type of signaling of the bearer network(e.g., UNI, PNNI, B-ISUP, etc.)

In accordance with certain embodiment(s) of the present invention, thenodes 405A,405B may be advantageously realized using, at least partly, amodified version of an existing/legacy telecommunications switch. Usingan existing telecommunications switch advantageously obviates any needto create code “from scratch” for the myriad of advanced callingfeatures that are already supported by the existing telecommunicationsswitch. Furthermore, in accordance with certain principles of thepresent invention, using an existing telecommunications switch enables agradual migration to a broadband transport mechanism such as ATM. Acall/connection control node 405A,405B and a respective connectioncontrol node 410A,410B pair together form a hybrid switch 420A/420B.

Referring now to FIG. 5, yet another exemplary scheme for utilizing abroadband network in conjunction with nodes having partially separatedfunctions in accordance with the present invention is illustratedgenerally at 500. The two hybrid switches 420A,420B are illustrated asbeing connected to the ATM network 215 by ATM links 505 (e.g., which maycorrespond to, for example, one or more of interface 300 c, interface300 e, and ATM physical link 341 of the embodiments) of FIG. 3 et seq.),e.g., via a connection control node 410. Each of the call/connectioncontrol node 405A and the connection control node 410A are connected toa Time Division Multiplexed (TDM) network 515 by TDM links 510 (e.g.,which may correspond to, for example, interface 300 d of embodiments) ofFIG. 3 et seq. [including alternative embodiment(s) of FIG. 3 et seq. asdescribed hereinabove with reference to the interface 300 d of FIG. 3];as well as interface 300 b/link 351, interfaces 300 b,300 c, and/orinterface 300 d/switch-to-switch link 360). The TDM network 515 maycorrespond to any of many so-called narrowband networks such as PSTN,PLMN, ISDN, etc. As indicated within the hybrid switch 420A, thecall/connection control node 405A is connected to the connection controlnode 410A via a TDM link 510 (e.g., which may correspond to, forexample, interface 300 b, interface 300 c, interface 300 d,switch-to-switch link 360, etc. of FIG. 3 et seq.) and an ethernet link520 (e.g., which may correspond to, for example, interface 300 a,interface 300 b, interface 300 c, switch-to-switch link 360, etc. ofFIG. 3 et seq.).

The hybrid switch 420 advantageously enables an existing switch inconjunction with an associated switch to facilitate the transport ofcall connections at least partly across a broadband network, such as theATM network 215. As illustrated in the scheme 500, the existing switchmay be realized using, for example, an AXE switch (available fromEricsson Inc.), and the associated switch may be realized using, forexample, an AXD 301 switch (also available from Ericsson Inc.). Thus,the hybrid switches 420A,420B may be realized using, for example, anEricsson Hybrid Switch (also available from Ericsson Inc.).

Referring now to FIG. 6, another exemplary hybrid switch with multipleports for switching a connection in accordance with the presentinvention is illustrated generally at 420. The hybrid switch 420includes a call/connection control node 405 and a connection controlnode 410 that are connected by linkage 605 (e.g., which may correspondto, for example, one or more of interface 300 a, interface 300 b,interface 300 c, interface 300 d, and switch-to-switch link 360 of theembodiment(s) of FIG. 3 et seq.). It should be noted that the thick linerepresenting the linkage 605 indicates that the linkage 605 may becomposed of more than one link. Information exchange across linkage 605permits the call/connection control node 405 to switch narrowband callsacross the switching fabric of the connection control node 410. Suchinformation exchange enables 64 kbit/sec, narrowband calls originatingand terminating in narrowband networks (e.g., one or more TDM networks515) to be trunked over broadband networks (e.g., one or more ATMnetworks 215) between hybrid switches 420. It should be noted that TDMas used herein, including the claims, encompasses and embracestime-division multiplexed protocols in general, and it is not limited toany particular TDM protocol.

The call/connection control node 405 includes input/outputs (I/Os) fortwo TDM links 510. Each TDM link 510 terminates at exchange termination(ET) equipment 610. Each ET equipment 610 is connected to a group switch(GS) 615 (e.g., which may correspond to, for example, the STM circuitswitch 335 of the embodiment(s) of FIG. 3 et seq.). Each ET equipment610 receives from the GS 615 data samples taken from multiple calls andmultiplexes this data into a stream of data sent out over a TDM link 510that connects the hybrid switch 420 to another node. The ET equipment610 also receives data from other nodes over the TDM link 510 anddemultiplexes this data into samples from separate calls to betransferred to the GS 615. The GS 615 is also connected to one or moresignaling terminals (STs) 620 (e.g., which may correspond to, forexample, the signaling terminals 337 of the embodiment(s) of FIG. 3 etseq.). The linkage 605 may include a TDM link 510 (not explicitly shownin FIG. 6) that connects an ET equipment 610 of the call/connectioncontrol node 405 with a circuit emulation-ET (CE-ET) equipment 625(e.g., which may correspond to, for example, the circuitemulation/translator 370 of the embodiment(s) of FIG. 3 et seq.) of theconnection control node 410.

The connection control node 410 includes I/Os for two TDM links 510.Each TDM link 510 terminates at CE-ET equipment 625 (e.g., which maycorrespond to, for example, the extension terminal ET 3462 (optionallyin conjunction with the circuit emulation/translator 350) of theembodiment(s) of FIG. 3 et seq.). Each CE-ET equipment 625 is connectedto an ATM switch 630 (e.g., which may correspond to, for example, theATM switch 345 of the embodiment(s) of FIG. 3 et seq.). The CE-ETequipment 625 terminates a TDM link 510 for the ATM switching fabric ofthe connection control node 410 by using circuit emulation. The circuitemulation, e.g., hardware on a CE-ET equipment 625 maps time slots froman E1 line into, for example, single streams of ATM adaptation layer 1(AAL1) cells. The CE-ET equipment 625 maps successive octets from asingle time slot to a single stream of AAL1 cells. The ATM switch 630 isalso connected to one or more ATM-ET equipments 635 (e.g., which maycorrespond to, for example, the extension terminal ET 346 ₁ of theembodiment(s) of FIG. 3 et seq.). Each ATM-ET equipment 635 terminatesan ATM link 505 to the ATM switching fabric of the connection controlnode 410.

The various ports/interfaces of the call/connection control node 405 andthe connection control node 410 enable the establishment of variousconnection paths in the hybrid switch 420. Connection paths may beestablished across the following exemplary points as enumerated in Table1:

TABLE 1 Connection Paths Establishable for FIG. 6. (1) point A-(I, J)-G(2) point A-(I, J)-H (3) point D-(J, I)-B (4) point E-(J, I)-B (5) pointC-(I, J)-G (6) point C-(I, J)-H (7) point D-(J, I)-F (8) point D-G (9)point D-H (10) point E-(J, I)-F (11) point E-G (12) point E-HTaking connection path “(6) point C-(I, J)-H”, for example, a connectionmay be established from point “C” at the TDM link 510, through two ETequipments 610 and the GS 615, to point “I”. The connection continuesfrom point “I” across the linkage 605 to point “J”. The connectioncontinues further from point “J” through a CE-ET equipment 625, the ATMswitch 630, and the ATM-ET equipment 635 to point “H” at the ATM link505.

Referring now to FIG. 7, a simplified block diagram of an exemplaryhybrid switch in accordance with the present invention is illustratedgenerally at 700. The hybrid switch at 700 includes a call/connectioncontrol node 405, which is shown connected to a TDM network 515 via aTDM link 510, and a connection control node 410, which is shownconnected to a TDM network 515 via a TDM link 510 and an ATM network 215via an ATM link 505. The call/connection control node 405 is connectedto the connection control node 410 via the linkage 605, which mayinclude one or more links. The connection control node 410 includesconnection control logic 705 and the ATM switch 630. The connectioncontrol logic 705 may be composed of, for example, hardware, software,firmware, some combination thereof, etc.

The ATM switch 630 is connected via link 710 to the GS 615 of thecall/connection control node 405. The link 710 may be utilized totransfer data information between the ATM switch 630 and the GS 615. Thecall/connection control node 405 also includes connection control logic715 to enable the call/connection control node 405 to switch calls(e.g., to or through the TDM network 515 directly connected thereto viathe TDM link 510) without the aid of the connection control node 410.The connection control logic 715 may also be composed of, for example,hardware, software, firmware, some combination thereof, etc. Thecall/connection control node 405 further includes call control logic720, which provides call control functions for the connection controlnode 410 as well as the call/connection control node 405. The callcontrol logic 720 may also be composed of, for example, hardware,software, firmware, some combination thereof, etc.

The call control logic 720 may provide call control functions to theconnection control node 410 by exchanging signaling information over alink 725. (It should be noted that either or both of the links 710 and725 may be composed of more than one link.) For example, for a callincoming to the connection control node 410 over the TDM link 510 fromthe TDM network 515, signaling information may be forwarded to the callcontrol logic 720 from the connection control logic 705 over the link725. The switching intelligence of the call control logic 720 executesapplicable call control functions and ascertains relevant call controlinformation (e.g., as explained further hereinabove with reference toFIG. 3 et seq.). This signaling information is sent from the callcontrol logic 720 over the link 725 to the connection control logic 705,which may thereafter switch the call data information of the incomingcall to/through the appropriate network (e.g., the ATM network 215). Thecall control functions of existing (e.g., STM) switches can therefore beadvantageously utilized by newer and faster (e.g., ATM) switches tothereby avoid needing to completely reprogram call control functionalityfor the newer switches.

It should be emphasized that the call/connection control node 405 iscapable of connecting directly to the TDM network 515 over the TDM link510 via the GS 615. Consequently, a hybrid switch architecture inaccordance with the present invention, by combining a call/connectioncontrol node 405 with a connection control node 410, enables thislogical node to communicate (i) with an existing TDM network 515 (e.g.,a PSTN network) using the GS 615 (e.g., an STM switch) and (ii) with abroadband network (e.g., the ATM network 215) over a broadband link(e.g., the ATM link 505) using a broadband switch (e.g., the ATM switch630). Providing such dual connectivity advantageously enables a networkto gradually migrate from a first network protocol (e.g., a narrowbandnetwork protocol) to a second network protocol (e.g., a broadbandnetwork protocol) while utilizing both existing call control logic(e.g., software, etc.) and existing connections to and within the firstnetwork (e.g., a narrowband network).

Referring now to FIG. 8, exemplary communications and connectionsbetween nodes in another simplified block diagram of an exemplary hybridswitch in accordance with the present invention are illustratedgenerally at 800. In the exemplary hybrid switch 420, thecall/connection control node 405 is connected to the connection controlnode 410 via the linkage 605 at points I and J. The linkage 605 may becomposed of multiple links. In this exemplary embodiment 800, asignaling information link 805 (e.g., which may correspond to, forexample, interface 300 a, interface 300 b, interface 300 c,switch-to-switch link 360, etc. of FIG. 3 et seq.) and a datainformation link 810 (e.g., which may correspond to, for example,interface 300 b, interface 300 c, interface 300 d, switch-to-switch link360, etc. of FIG. 3 et seq.) are illustrated as connecting thecall/connection control node 405 to the connection control node 410. Thesignaling information link 805 may carry signaling communicationsbetween the call/connection control node 405 and the connection controlnode 410, and the data information link 810 may carry datacommunications between the call/connection control node 405 and theconnection control node 410. Such data communications may include voiceor data calls, for example.

In an exemplary embodiment, the signaling information link 805 isrealized using two ethernet links. One ethernet link may be used fortransmitting signaling information from the call/connection control node405 to the connection control node 410 while the other ethernet link maybe used for transmitting signaling information from the connectioncontrol node 410 to the call/connection control node 405. It should beunderstood that ethernet links are typically duplex in nature and thatany ethernet links employed in any particular embodiment(s) inaccordance with the present invention may also be duplex. The datainformation link 810 may be realized using a TDM link. For example, thedata information link 810 may be composed of one or more E1 lines.Communications necessary and/or beneficial to establishing the variousconnections described hereinabove with reference to FIGS. 6 and 7, forexample, may be effectuated across the signaling information link 805and the data information link 810. Advantageously, because separatelinks are employed between the nodes 405 and 410, signaling informationand data information may be transferred therebetween across links 805and 810, respectively, without needing to specify whether thetransmitted information pertains to signaling or to data.

As illustrated generally at 800, the call/connection control node 405 isconnected to two TDM networks 515, and the connection control node 410is connected to two TDM networks 515 as well as two ATM networks 215. Itshould be noted that the number of networks to which the nodes 405 and410 are connected is exemplary only. The flexibility of the hybrid node420 advantageously enables calls to be incoming at either of the nodes405 and 410 and to be forwarded via a connection of either of the nodes405 and 410. In other words, a narrowband call incoming to theconnection control node 410 (at point D) or a broadband call (e.g., anarrowband call being carried by a broadband transport mechanism, etc.)incoming to the connection control node 410 (at point E) may beforwarded from the connection control node 410 (as a narrowband orbroadband call at point G or point H, respectively) or from thecall/connection control node 405 as a narrowband call (e.g., at pointF). Furthermore, a narrowband call incoming to the call/connectioncontrol node 405 (at point C) may be forwarded from the call/connectioncontrol node 405 as a narrowband call (at point F) or from theconnection control node 410 (e.g., as a narrowband or broadband call atpoint G or point H, respectively). It should be noted that othercombinations of ingress and egress (e.g., other connection paths) arepossible.

By way of a first example but not limitation, assume that a call (or,more generally, a communication) is incoming to the connection controlnode 410 from a TDM network 515 at point D. The signaling informationrelated to the call (e.g., an ISUP Initial Address Message (IAM)) isencapsulated into ATM cells (e.g., at the CE-ET equipment 625 at pointD) and passed to the ATM switch 630. Advantageously, the signalinginformation may therefore be piped through the connection control node410 and over the (e.g., ethernet-based) signaling information link 805without reformatting after being de-packaged from ATM cells (e.g., atthe CE-ET equipment 625 at point J). The signaling information thereforeneed not be modified inasmuch as it may be transported through“transparent” pipes across the ATM switching fabric of the connectioncontrol node 410 (e.g., using a permanent virtual path connection (PVPC)pipe or similar, etc.).

When the GS 615 and associated call control logic (not explicitly shownin FIG. 8) receive the signaling information of the incoming call, thesignaling information is analyzed (e.g., by an ST 620 at point A orpoint B). The traffic call handling is performed by, for example,performing a B-number analysis, accessing an interactive voice responsesystem, contacting an Intelligence Network (IN) node 815 (e.g., for“(800)” call routing, etc.), consulting a database of bearercapabilities for destination and/or transit nodes, etc. If, incontradistinction to the example described hereinabove with reference toFIG. 3A, the call/connection control node 405 determines that the callshould not or can not be routed through a broadband ATM transportmechanism, then the call/connection control node 405 instructs theconnection control node 410 (e.g., over the signaling information link805) to route the data information of the call to (and through) thecall/connection control node 405.

The data information of the call is routed through the connectioncontrol node 410 from point D to point J (e.g., by piping the datainformation via a semi-permanent connection through the switching fabricof the ATM switch 630). It should be noted that the data information maybe propagated through the connection control node 410 withoutreformatting by, for example, encapsulating the data information in ATMcells. Thereafter, the data information is forwarded from point J topoint I over the data information link 810 in, for example, a TDMformat. The ET equipment 610 receives the data information of the call,and the GS 615 switches it toward the appropriate TDM network 515 (e.g.,through an ET equipment 610 to a point C or a point F) in accordancewith the earlier traffic call analysis.

By way of a second example but not limitation, assume that a call isincoming to the call/connection control node 405 from a TDM network 515at point C. The call/connection control node 405 performs a traffic callanalysis based on signaling information of the call. If the analysisindicates that the call can (and optionally should) be sent over abroadband transport mechanism, the call/connection control node 405 candirect the incoming call through the connection control node 410 andthen to an ATM network 215, instead of directing the call to a TDM nodein a TDM network 515 (e.g., through the ET equipment 610 at the pointF). In this regard, the GS 615 may switch the call signaling informationto the ATM switch 630 via the signaling information link 805 and thecall data information to the ATM switch 630 via the data informationlink 810 (and appropriate ET equipment 610 and CE-ET equipment 625 atpoint I and point J, respectively). The ATM switch 630 may thereaftersend the signaling information of the call over permanent connectionsset up in the broadband ATM network 215 and the data information of thecall over, e.g., call-specific connections in the broadband ATM network215 (via an ATM-ET equipment 635 at point E or point H).

Referring now to FIG. 9, an exemplary method in flowchart form forcommunicating between nodes in a hybrid switch in accordance with thepresent invention is illustrated generally at 900. In the exemplarymethod of flowchart 900, an incoming call is initially received at afirst node (step 905). The first node sends signaling informationrelated to the incoming call to a second node via a first link (step910). The second node, which may provide call control for the firstnode, processes the signaling information (step 915) to determine howand to where the incoming call is to be routed. The second node sendsinstructions to the first node (e.g., via the first link) (step 920)directing the first node on how/where to route the incoming call.Assuming that the second node determined that the incoming call shouldbe routed as an outgoing call from the second node (at step 915) andthat the instructions sent to the first node (at step 920) so indicated,data information related to the incoming call is sent from the firstnode to the second node via a second link (step 925).

Alternatively, an incoming call can be received at a node capable ofprocessing the corresponding signaling information. Accordingly, bothsignaling information and data information corresponding to the incomingcall may be sent to an associated node via first and second links,respectively, if the node receiving the incoming call determines that itis appropriate to do so (e.g., as described hereinabove in the secondexample referencing FIG. 8). The call control functions of existing(e.g., STM) switches can therefore be advantageously utilized by newerand faster (e.g., ATM) switches to thereby avoid needing to completelyreprogram the call control functionality for the newer switches.Furthermore, hybrid switches including both narrowband and broadbandswitches enable greater versatility for switching communications betweenbroadband and narrowband transport mechanisms. For example, a hybridswitch may receive a communication that is being transported in anarrowband format and forward the communication in a broadband format,or vice versa. This ability is particularly advantageous for enabling agradual migration in a network from being primarily or entirelynarrowband to being primarily or entirely broadband.

Referring now to FIGS. 10A–10E, a first set of exemplary trafficscenarios for a hybrid switch in accordance with the present inventionis illustrated. In FIG. 10A, a hybrid switch 420 is illustrated as beingconnected to two local exchange/transit exchange (LE/TE) nodes via TDMlinks, which may operate using an “N-ISUP” protocol, for example. Thehybrid switch 420 is illustrated as receiving and forwarding acommunication 1000. It should be understood that the detailed trafficscenarios illustrated in FIGS. 10B–10E are also applicable to otherinstances besides when a hybrid switch 420 is directly connected to alocal exchange/transit exchange node on both sides of a communication1000. For instance, the traffic scenarios of FIGS. 10B–10E areapplicable whenever both the incoming and the outgoing side of acommunication are transported on a narrowband transport mechanism suchas TDM.

In FIG. 10B, the communication 1010 (which represents a particulartraffic scenario and/or portion of the communication 1000) may beterminated and switched entirely within the narrowband portion of thehybrid switch 420. In FIG. 10C, the incoming side of a communication1020 is terminated in the narrowband portion of the hybrid switch 420while the outgoing side is terminated at the broadband portion (e.g.,using a circuit emulation (CE) board). The switching occurs partlywithin the narrowband portion and partly within the broadband portion ofthe hybrid switch. In FIG. 10D, both of the incoming and the outgoingsides of a communication 1030 are terminated in the broadband portion ofthe hybrid switch 420. In this scenario, a, e.g., circuit emulationboard is utilized on both the ingress and the egress sides of the, e.g.,TDM connection. The switching may be effectuated entirely within theswitching fabric of the broadband portion. In FIG. 10E, the incomingside of a communication 1040 is terminated by the broadband portion ofthe hybrid switch 420 whereas the outgoing side is terminated at thenarrowband portion. Switching of the communication 1040 is thereforeeffectuated partly within the broadband portion (e.g., using an ATMswitch 630) and partly within the narrowband portion (e.g., using a GS615) of the hybrid switch 420.

Referring now to FIGS. 10F–10K, a second set of exemplary trafficscenarios for a hybrid switch in accordance with the present inventionis illustrated. In FIG. 10F, multiple hybrid switches 420 areillustrated as being connected to each other and ultimately to two localexchange/transit exchange nodes. The hybrid switches 420 are illustratedas receiving and forwarding a communication 1000. A connection betweentwo hybrid switches 420 may be realized using an ATM link, which maycarry an “N-ISUP” protocol thereon, for example. A connection between ahybrid switch 420 and a local exchange/transit exchange may be realizedusing a TDM link, which may operate using an “N-ISUP” protocol, forexample.

It should be understood that the detailed traffic scenarios illustratedin FIGS. 10G–10J are also applicable to other instances besides when ahybrid switch 420 is directly connected to a local exchange/transitexchange node on a single side of a communication 1000. For instance,the traffic scenarios of FIGS. 10G–10J are applicable whenever one sideof a communication is transported on a narrowband transport mechanismsuch as TDM and the other side of the communication is transported on abroadband transport mechanism such as ATM. Likewise, it should beunderstood that the detailed traffic scenario illustrated in FIG. 10K isalso applicable to other instances besides when a hybrid switch 420 isdirectly connected to hybrid switches 420 on both sides of acommunication 1000. For instance, the traffic scenario of FIG. 10K isapplicable whenever both sides of a communication are transported on abroadband transport mechanism such as ATM.

In FIG. 10G, a communication 1050 is terminated at the incoming (e.g.,TDM) side by the narrowband portion of the hybrid switch 420. Theswitching of the communication 1050 may be performed by both thenarrowband and the broadband portions after accommodation of thediffering formats (e.g., by a circuit emulation board). The terminationof the outgoing (e.g., ATM) side of the communication 1050 iseffectuated (e.g., by an exchange termination (ET) board) at thebroadband portion of the hybrid switch 420. In FIG. 10H, the incomingside of a communication 1060 is terminated (e.g., by a circuit emulationboard for a narrowband transport format) at the broadband portion of thehybrid switch 420. Switching of the communication 1060 may be performedentirely within the switching fabric of the broadband portion of thehybrid switch, and termination (e.g., by an exchange termination boardfor a broadband transport format) of the outgoing side of thecommunication 1060 may be accomplished by the broadband portion as well.

In FIG. 10I, the incoming side of a communication 1070 is terminated(e.g., by an exchange termination board for a broadband transportformat) at the broadband portion of the hybrid switch 420. Switching ofthe communication 1070 may be performed entirely within the switchingfabric of the broadband portion of the hybrid switch 420, andtermination (e.g., by a circuit emulation board for a narrowbandtransport format) of the outgoing side of the communication 1070 may beaccomplished by the broadband portion as well. In FIG. 10J, acommunication 1080 is terminated at the incoming (e.g., ATM) side by thebroadband portion of the hybrid switch 420 (e.g., using an exchangetermination board). The switching of the communication 1080 may beperformed by both the narrowband and the broadband portions afteraccommodation of the differing formats (e.g., by a circuit emulationboard). The termination of the outgoing (e.g., TDM) side of thecommunication 1080 is effectuated at the narrowband portion of thehybrid switch 420.

In FIG. 10K, the hybrid switch may act as a “pure transit node” for ATMconnections, such as the illustrated portion of the communication 1000,which is denoted as a communication 1090. Both of the incoming and theoutgoing sides of the communication 1090 are terminated by the broadbandportion of the hybrid switch 420 (e.g., by two exchange terminationboards). Also, the communication 1090 may be switched entirely by theswitching fabric (e.g., as realized by an ATM switch 630) of thebroadband portion of the hybrid switch 420. As also described andalluded to with reference to, for example, FIG. 6 hereinabove, a hybridswitch 420 may establish various connection paths within to therebyenable a myriad of combinations of external ingress points and externalegress points for different types of communications. The hybrid switch420 may thus receive and forward communications 1000 in any combinationof incoming and outgoing narrowband and broadband formats toaccommodate, for example, the next node along the communication path, anode that is proximal to the final destination of the communication1000, etc.

Referring now to FIG. 11, an exemplary outgoing communication formatselection for a hybrid switch in accordance with the present inventionis illustrated generally at 1100. An incoming communication 1105 isillustrated as being either broadband (e.g., ATM formatted) ornarrowband (e.g., TDM formatted). The hybrid switch 420, as describedhereinabove with reference to FIGS. 10A–10K, for example, may forwardthe communication 1105 as either an ATM communication or a TDMcommunication. (It should be understood that an outgoing TDMcommunication may be terminated by either the narrowband portion or thebroadband portion of the hybrid switch 420. However, this detail is notdirectly addressed further in the context of FIG. 11.) The hybrid switch420 may forward the communication on the outgoing side according to anyof various algorithms. For example, the hybrid switch may forward allincoming communications 1105 as outgoing TDM communications 1115 (e.g.,if the hybrid switch 420 is the first or one of the first hybridswitches to be installed in a traditionally narrowband network) or asoutgoing ATM communications 1120 (e.g., if the hybrid switch 420 is thelast or one of the last hybrid switches to be installed in a formallynarrowband network). Refer also to the text hereinabove describing FIG.3H.

Alternatively, the hybrid switch 420 may consult a table 1110 thatprovides an indication as to the viability and/or desirability offorwarding the communication 1105 in either a broadband or a narrowbandformat. For example, the table 1110 may indicate whether a nodeassociated with the destination terminal 1155 or 1170 is capable ofbroadband transport. The table 1110 may also or in the alternativeindicate whether any nodes between the hybrid switch 420 and thedestination terminal 1155 and 1170 are capable of broadband transport.An exemplary embodiment for table 1110 is discussed hereinabove withreference to, for example, FIG. 3A, Events E8 and E9, and may involvethe ascertainment of the bearer type (of either or both of the incomingside of the communication and the destination terminal). It should benoted that the table 1110 may be realized, instead of being part of thenarrowband portion of the hybrid switch 420 but separate from the GS asillustrated, as part of the GS (e.g., the GS 615), as any part of thebroadband portion (e.g., the ATM switch 630), as another part of thehybrid switch 420, or even at an external location (e.g., an IN node),etc.

Alternatively, instead of relying on information in a table 1110, thehybrid switch may query a node at or proximate to the destination node,may send a test signal/communication, etc. Regardless, if the hybridswitch 420 determines that there is a broadband node associated with thedestination terminal, the hybrid switch 420 may elect to forward theincoming communication 1105 as a broadband (e.g., ATM) communication1120. The hybrid switch 420′ receives the incoming broadbandcommunication 1120 and forwards an outgoing narrowband (e.g., TDM)communication 1160 to a local exchange node 1165 (e.g., which maycorrespond to, for example, an access node 322, etc. of FIG. 3 et seq.),which connects to the destination terminal 1170 (e.g., which maycorrespond to, for example, a terminal 324, etc. of FIG. 3 et seq.).

If, on the other hand, the hybrid switch 420 determines that there isnot a broadband node associated with the destination terminal, thehybrid switch 420 may elect to forward the incoming communication 1105as a narrowband (e.g., TDM) communication 1115. However, the hybridswitch 420 may optionally include provisions for determining that one ormore (e.g., a sufficiently high enough number of intervening nodes havebroadband capability, a sufficiently shorter route may be defined acrossintervening broadband-enabled network nodes, etc.) intervening broadbandnodes may be advantageously utilized along the overall communicationpath. If such a determination is made, the hybrid switch 420 may electto forward the incoming communication 1105 as a broadband (e.g., ATM)communication 1125 through a broadband-enabled network portion 1130.Regardless, the communication is or ultimately becomes/is converted to anarrowband (e.g., TDM) communication and is submitted as narrowbandcommunication 1135 to the narrowband node 1140. The narrowband node 1140forwards the incoming narrowband communication 1135 as an outgoingnarrowband (e.g., TDM) communication 1145 to a local exchange 1150(e.g., which may correspond to, for example, an access node 322, etc. ofFIG. 3 et seq.), which connects to the destination terminal 1155 (e.g.,which may correspond to, for example, a terminal 324, etc. of FIG. 3 etseq.).

Referring now to FIG. 12, exemplary interactions between a hybrid switchand other telecommunications technology in accordance with the presentinvention are illustrated generally at 1200. The hybrid switch 420 of1200 illustrates the traffic scenarios or communication portions1010–1090 of communication 1000 (of FIGS. 10A–10K). Communication 1205(illustrated generally as a line or loop) enables a communication1010–1090 according to any of the various traffic scenarios to accesstelecommunications technology using TDM communication and a STM switch(e.g., a GS 615). For example, one or more IN nodes 815 of an IN (notexplicitly shown in FIG. 12) may be accessed via the communication 1205.Many telecommunications services and features may be utilized byaccessing the IN. A DTMF receiver 1210, for example, may be accessed forpassword and account number reception and for sending announcements fromthe IN. Generally, specialized resource function (SRF) and servicecontrol function (SCF) features are accessible via the IN node 815.These and other IN features are represented generally by the other block1215. Access to the IN node 815 may be accomplished during the callestablishment phase. Thereafter, routing of the communication 1000 mayoptionally be maintained through the narrowband portion of the hybridswitch 420. Regardless, the communication 1000 may be routed through thenarrowband portion (e.g., the GS 615) during an active call phase inorder to access IN features.

The communication 1205 may also enable access to the operator 1220 forthe communication 1000 (of FIGS. 10A–10K) The operator 1220 may handlethe telecommunications situation and thereafter route the connectionfurther along communication 1205 to implement one of the illustratedtraffic scenarios. Alternatively (e.g., depending on how the operator1220 handles the telecommunications situation), the operator 1220 mayindependently forward the connection towards, e.g., another exchange asindicated by arrow 1225. The communication 1205 may also enable accessto legal intercept (LI) equipment 1230. It should be noted that withrespect to FIG. 12, as well as other FIGS. described herein, certainelements may be moved, changed in number, etc. without departing fromthe scope of the present invention. For example, with regard to thehybrid switch 420 of FIG. 12, only two ET equipments may be associatedwith the GS (instead of the four illustrated), and the CE equipmentbetween the GS and the ATM switch may be more closely associated withthe ATM switch than the GS (e.g., as illustrated in FIG. 11).

The hybrid nature of the hybrid switch 420, in addition to enabling agradual migration from a narrowband-oriented network to abroadband-oriented network, also enables seamless integration withnetworks of other carriers, networks of mobile systems, and networksthat are international (all of which are designated generally by theexternal networks 1240). The external networks 1240 currently operate inaccordance with TDM principles (or at least they are designed tointerface with other networks using TDM principles), and they maycontinue to do so for quite some time into the future. The hybrid switch420, while providing the ability to transport communications on abroadband transport mechanism, also maintains the ability to utilize anarrowband transport mechanism and the ability to interface withexternal networks 1240 using traditional protocols. For example,communication 1205 enables outgoing connections (as represented by arrow1235) and incoming connections (as represented by arrow 1245) betweenthe hybrid switch 420 and the external networks 1240.

Referring now to FIG. 13, an exemplary traffic scenario migration for ahybrid switch in accordance with the present invention is illustratedgenerally at 1300. The hybrid switch 420 may be “installed” in anexisting network that utilizes, at least primarily, a narrowbandtransport mechanism. The hybrid switch 420 may be “installed”, forexample, by augmenting an existing TDM switch with ATM switching fabric.When the hybrid switch 420 is initially installed, especially if it isone of the first such switches installed, the hybrid switch may beactivated or set up to operate entirely or predominantly within a firstexemplary mode. Such a first exemplary mode may entail receiving acommunication 1305 (e.g., as incoming TDM) and forwarding thecommunication 1305 (e.g., as outgoing TDM) using the switching fabric(e.g., a GS 615) of the existing narrowband switch. Gradually, asadditional broadband-enabled nodes are “brought on-line”, the hybridswitch 420 may enter a second exemplary mode. Such a second exemplarymode may entail receiving a communication 1310 (e.g., as incoming TDM)and forwarding the communication 1310 (e.g., as outgoing ATM) using theswitching fabric of the existing narrowband switch as well as theswitching fabric (e.g., an ATM switch 630) of the broadband switch.

As the hybrid switch 420 of 1300 begins to receive incomingcommunications that use a broadband transport mechanism such as ATM, thehybrid switch 420 may enter a third exemplary mode. Such a thirdexemplary mode may entail receiving a communication 1315 (e.g., asincoming ATM) and forwarding the communication 1315 through theswitching fabric of the broadband switch and the switching fabric of thenarrowband switch to be handled by narrowband telecommunicationstechnology and/or telecommunications technology with narrowbandinterface(s). For example, the communication 1315 may be forwarded fromthe narrowband switch as communication 1315′ to a voice response unit1320 to provide voice response service to the communication 1315 thatoriginally arrived at the hybrid switch 420 using a broadband transportmechanism. Alternatively, the communication 1315 may be forwarded fromthe narrowband switch as communication 1315″ (as indicated by the arrowso labeled) to external network(s) 1240. If the communication 1315 is tocontinue within the network of the hybrid switch 420 (or otherwiseforwarded as a broadband connection therefrom), the communication 1315′is returned to the narrowband switching fabric (e.g., after beingserviced by the voice response unit 1320 or other such existingnarrowband features) and forwarded to and through the broadbandswitching fabric as the communication 1315′ (e.g., as outgoing ATM).

Eventually, as the network becomes wholly or primarily a broadbandtransport mechanism network (optionally including broadband provision ofIN-type services, etc.), the hybrid switch 420 of 1300 may enter afourth exemplary mode. Such a fourth exemplary mode may entail receivinga communication 1325 (e.g., as incoming ATM) and forwarding thecommunication 1325 (e.g., as outgoing ATM) using the switching fabric ofthe broadband portion of the hybrid switch 420. It should be understoodthat the four modes illustrated and described herein with reference toFIG. 13 are exemplary only. Modes may be added, subtracted, orsubstituted for the four exemplary modes depending, for example, on thepercentage of the network that has been upgraded to broadband.Furthermore, the modes may be activated in a different order depending,for example, on whether or not the hybrid switch in question is a“transit-type” node.

Referring now to FIG. 14, an exemplary method in flowchart form forenabling a gradual migration from a primarily narrowband network to aprimarily broadband network in accordance with the present invention isillustrated generally at 1400. Initially, a network node (e.g., a hybridswitch 420) receives an incoming communication that includes anidentifier corresponding to a destination terminal (e.g., a destinationterminal 1155 and 1170 (of FIG. 11)) (step 1405). The incomingcommunication may be transported, for example, on a broadband ornarrowband mechanism. The identifier that corresponds to the destinationterminal is analyzed (step 1410). The identifier may correspond to, forexample, a B-number, and the identifier may be analyzed, for example, ina narrowband portion of the network node. The analysis may include adetermination as to whether or not the identifier is associated with anode having broadband capability (step 1415). If not, then thecommunication may be forwarded over a narrowband transport mechanism(step 1420) and ultimately to the destination terminal.

If, on the other hand, it is determined that the identifier isassociated with a node having broadband capability (at step 1415), thenthe communication may be forwarded over a broadband transport mechanism(step 1425) and ultimately to the destination terminal. The identifiermay be associated with a node when, for example, the node is the mostproximate node (or the most proximate non-local exchange and/or non-endoffice node) to the destination terminal. The identifier, in addition toor in the alternative, may be associated with a node when the node issomewhere between the analyzing node and the destination terminal, butthe node is sufficiently far from the analyzing node and sufficientlyclose to the destination terminal so as to warrant diverting (ifnecessary) the communication onto a broadband transport mechanism. Theanalysis may involve accessing a table (or other data structure) (e.g.,a table 1110), which may be gradually updated as nodes in the networkare upgraded to provide broadband transport. In an alternativeembodiment, a communication may only be forwarded using a broadbandtransport mechanism (e.g., in step 1425) if a node having broadbandcapability is also associated with an identifier that corresponds to anoriginating terminal and/or if the incoming communication “arrives” overa broadband transport mechanism. In yet another alternative, thebroadband capability of a node associated with the identifier thatcorresponds to the originating terminal may be another factor to accountfor when analyzing the proximity of the node associated with theidentifier of the destination terminal. A hybrid switch operated inaccordance with certain principles of the present invention thereforeenables a gradual migration from a narrowband-oriented network to abroadband transport mechanism-oriented network.

Referring now to FIG. 15, an exemplary tri-level nodal environment inaccordance with the present invention is illustrated generally at 1500.A call/connection control node 405 (e.g., which may correspond to, forexample, PSTN/ISDN nodes 330 of the embodiment(s) of FIG. 3 et seq.) isillustrated connected to a modified connection control node 410′ (e.g.,which may correspond to, for example, ATM node 340 ₇₋₁ Of theembodiment(s) of FIG. 3 et seq.) via line 1510 (e.g., which maycorrespond to, for example, interface 300 a and/or interface 300 d ofthe embodiment(s) of FIG. 3 et seq.). The modified connection controlnode 410′, in the exemplary tri-level nodal environment 1500, includesan interworking function (IWF) 1505 (e.g., which may correspond to, forexample, an IWF 344 ₇₋₁ of the embodiment(s) of FIG. 3 et seq.). The IWF1505 may be composed of, for example, hardware, software, firmware, somecombination thereof, etc.

The IWF 1505 may include emulation and mapping capabilities. Forexample, the IWF 1505 may include the ability to emulate a switchinterface for the call/connection control node 405. Advantageously, thiseliminates any absolute requirement to modify the call/connectioncontrol node 405 because the call/connection control node 405 is able toact and interact as if it is functioning within a traditionaltelecommunications network. The IWF 1505 may also include the ability tomap/translate one network address into or to another network address.The modified connection control node 410′ is illustrated connected tomultiple connection control nodes 410 (e.g., which may correspond to,for example, ATM node 340 ₇₋₂, ATM node 340 ₇₋₃, etc. of theembodiment(s) of FIG. 3 et seq.) via lines 1515 (e.g., which maycorrespond to, for example, interfaces 300 a and/or interfaces 398 ofthe embodiment(s) of FIG. 3 et seq.). In the exemplary tri-level nodalenvironment 1500, the call/connection control node 405 mayadvantageously provide/share its switching intelligence with more thanone connection control node 410. It should be understood that thevarious nodes may be physically co-located, physically separated, etc.

Referring now to FIG. 15A, a first exemplary tri-level nodal environmentalternative in accordance with the present invention is illustratedgenerally at 1525. In the first exemplary tri-level nodal environmentalternative 1525, the call/connection control node 405 is incommunication with the modified connection control node 410′ via a firstline 1530 and a second line 1535. The first line 1530 and the secondline 1535 may be used for communicating signaling information and datainformation, respectively, between the call/connection control node 405and the modified connection control node 410′, which has the IWF 1505.Also illustrated in the first exemplary tri-level nodal environmentalternative 1525 is an ATM network 215 cloud interconnecting themodified connection control node 410′ and the connection control nodes410. In other words, the modified connection control node 410′ need notemploy direct and dedicated links to the individual connection controlnodes 410. It should be understood that the ATM network 215 mayalternatively be realized as any circuit-switched network.

Referring now to FIG. 15B, a second exemplary tri-level nodalenvironment alternative in accordance with the present invention isillustrated generally at 1550. In the second exemplary tri-level nodalenvironment alternative 1550, a “streamlined” tri-level nodalenvironment is illustrated. The modified call control node 405′ does notinclude connection control (e.g., it was designed and built without suchconnection control, it had its connection control removed or renderedinoperable, etc.), and no single connection control is directlyassociated with (or co-located with) the IWF (node) 1505. The switchingintelligence of the modified call control node 405′ operates in a firstaddress space, which is designated address space A 1555. The switchingfabric of the multiple connection control nodes 410, on the other hand,operate in a second address space, which is designated address space B1560. The IWF 1505 maps/translates the addresses of the address space A1555 to the addresses of the address space B 1560 so as to enable theswitching intelligence of the modified call control node 405′ to providecall control to the switching fabric of the multiple connection controlnodes 410.

It should be understood that while the address spaces A 1555 and B 1560are illustrated only in the second exemplary tri-level nodal environmentalternative 1550, they are also applicable to the exemplary tri-levelnodal environment 1500 as well as the first exemplary tri-level nodalenvironment alternative 1525. It should also be understood that thedifferent aspects illustrated in the various embodiments of FIGS. 15,15A, and 15B may be interchanged without departing from the presentinvention. For example, a circuit-switched network cloud (e.g., the ATMnetwork 215) may interconnect the multiple connection control nodes 410in any or all embodiments embraced by the present invention.

Referring now to FIG. 15C, an exemplary interworking function inaccordance with the present invention is illustrated at 1505. The IWF1505 includes an emulator 1580 and a mapper (or translator) 1585. Theemulator 1580 emulates an interface to which the call/connection controlnode 405 “expects” to be connected. In other words, the emulator 1580may provide an interface that the call/connection control node 405 isalready designed to utilize and/or interact with. Advantageously, thiseliminates or minimizes or at least reduces the need to modify thecall/connection control node 405. It should be noted that the interfacemay be equivalent to a GS input/output (I/O), E1/T1 trunk lines, etc.The mapper 1585 provides a mapping (or more generally a correspondence)between addresses of a first address space and addresses of a secondaddress space.

The mapper may map (or more generally a correspondence may beestablished between) address space A 1555 (of FIG. 15B) to the addressspace B 1560. For example, one or more of the addresses A1 . . . An ofthe address space A 1555 may be mapped to one or more of the addressesB1 . . . Bn of the address space B 1560. As a specific instance, theaddress A3 may be mapped to the address B1. In exemplary embodiment(s),the address space A 1555 may include 10-digit B-numbers, and the addressspace B 1560 may include ATM identifiers such as VPIs and VCIs. Otherexemplary address space realizations are also embraced by the presentinvention.

Referring now to FIG. 16, an exemplary tri-level nodal environmentimplementation in accordance with the present invention is illustratedgenerally at 1600. A telecommunications node (TN) 1605 (e.g., which maycorrespond to, for example, a call/connection control node 405 of theembodiment(s) of FIG. 15 et seq.) is shown connected to media gatewayfunctionality 1610 (e.g., which may correspond to, for example, amodified connection control node 410′ of the embodiment(s) of FIG. 15 etseq.). The TN (a.k.a. legacy switch (LS)) 1605 may have a circuit switchsuch as a GS 615 (not explicitly shown in FIG. 16). The media gatewayfunctionality 1610 may include a media gateway (MG) 1615, which may havea packet switch such as an ATM switch 630, and mediation logic (ML) 1620(e.g., which may correspond to, for example, an IWF 1505 of theembodiment(s) of FIG. 15 et seq.).

The media gateway functionality 1610 is illustrated as being connectedto multiple MGs 1625 (e.g., which may correspond to, for example, themultiple connection control nodes 410 of the embodiment(s) of FIG. 15 etseq.). Each of the MGs 1625 may be responsible for handling one or moredifferent types of media. The media, and nodes corresponding thereto,may include, for example, a remote subscriber switch (RSS) node 1630A, aV5.2 interface access network (V5.2) node 1630B, a local exchange (LE)node 1630C, a primary rate access (PRA) node 1630D, etc. An MG 1625 (oran MG 1615) may convert media provided in one type of network to theformat requirements of another type of network.

Exemplary and/or appropriate protocols for the links between the variousillustrated nodes (including the gateways) are illustrated at theexemplary tri-level nodal environment implementation 1600. As anexplanatory example, the connections between the media gatewayfunctionality 1610 and the multiple MGs 1625 may be ATM-ET to ATM-ETPVPC pipes defined through an ATM network to carry signalinginformation. A PVPC is an ATM connection in which the switching isperformed only on the VPI field of each cell. A PVPC is termed“permanent” because it is provisioned through a network managementfunction and maintained (or left up) indefinitely. The signalinginformation between the media gateway functionality 1610 and any one ormore of the MGs 1625 may be effectuated transparently over a PVPC pipe.Such a PVPC pipe is at least similar to one establishable through theswitching fabric of a connection control node 410 for transparentlypiping signaling information to the switching intelligence of acall/connection control node 405 (as alluded to hereinabove withreference to FIG. 3 et seq.).

Referring now to FIGS. 17A and 17B, two other exemplary tri-level nodalenvironment implementations in accordance with the present invention areillustrated generally at 1700 and 1750, respectively. The exemplarytri-level nodal environment implementations 1700 and 1750 include callservers 1705. The call servers 1705 each include a TN 1605 and ML 1620.Each call server 1705 may control one or more MGs 1625 (denoted as “MGW”in FIGS. 17A and 17B) via the packet-switched network cloud, such as anATM network 215. Each call server 1705, being based on pre-existing TNs1605 in certain exemplary embodiment(s), may only handle a finite numberof MGs 1625. Accordingly, a given tri-level nodal environment may needmore than one call server 1705, as indicated by the two call servers1705 illustrated in the exemplary tri-level nodal environmentimplementation 1750.

The bearer services for call data information are provided by thepacket-switched broadband network (e.g., via encapsulation), and thetelecommunications services/call control may be transported over thispacket-switched (broadband) network in an un-modified format (e.g.,transparently in pipes), as indicated by the dashed lines. For example,control communications to the private branch exchange (PBX) nodes 1710Aare effectuated using DSS1, control communications to the generic accessnodes (AN) 1710B are effectuated using V.5, and control communicationsto the LE nodes 1630C are effectuated using ISUP. Likewise or similarly,the two call servers 1705 may communicate therebetween using a bearerindependent call control (BICC) protocol that may be transported overthe packet-switched network. It should be emphasized that TDM as usedherein, including the claims, encompasses and embraces time-divisionmultiplexed protocols in general, and it is not limited to anyparticular TDM protocol, including the exemplary 2M PCM link definitionof FIGS. 17A and 17B.

With reference now to FIGS. 18A and 18B, two exemplary call setups in anexemplary tri-level nodal environment implementation in accordance withthe present invention are illustrated generally at 1800 and 1850,respectively. In the exemplary call setup 1800, a TN 1605 determinesthat a communication path between points A and B are needed for a call.The TN 1605 therefore instructs the ML 1620 to establish a path betweenthe points A and B. The instruction may include direction(s) forestablishing such a path in a TDM network. The ML 1620, applying thepoints A and B and/or the direction(s) to a mapping data structure forexample, determines how to establish a communication path between pointsA and B. The ML 1620 then instructs/requires that such a communicationpath be established (e.g., added) in the broadband network of which theMG 1625 is a part. In the exemplary call setup 1800, an intra MG callsetup case is illustrated, so the single MG 1625 that is illustrated iscapable of establishing the communication path.

In the exemplary call setup 1850, on the other hand, a multi-MG (butintra domain) call setup case is illustrated, so more than a single MG1625 is required to establish the communication path. Specifically,after the ML 1620 receives the instruction (and possibly thedirection(s)) from the TN 1605, the ML 1620 determines that thecommunication path needs to extend between at least two MGs 1625.Namely, the MGs 1625 that include the points A and B need to beinterconnected, optionally with no intervening MG(s) 1625. In theexemplary call setup 1850, the ML 1620 then instructs/requires that suchan interconnection for the communication path be established (e.g.,added) in the broadband network between the MG 1625AC′ and the MG1625D′B, as indicated by the dashed line. The MGs 1625AC′ and 1625D′Balso complete the communication path between point A and point B byestablishing interconnections between points A and C′ and points D′ andB, respectively. By determining a communication path and/or institutinga routing of a communication path between point A and point B through apacket-switched (broadband) network, the ML 1620 effectively maps fromone address space to another address space.

Referring now to FIG. 19, exemplary communication path configuring in anexemplary tri-level nodal network in accordance with the presentinvention is illustrated generally at 1900. The entities responsible forconfiguring various communication paths in the exemplary tri-level nodalnetwork 1900 are indicated by the type of line (e.g., solid, dashed,thick, thin, etc.) illustrating/representing the particularcommunication path. The signaling link parts represented by the solidthick lines (also labeled “(A)”) are configured by TN 1605 commands. Thesignaling link parts represented by the solid thin lines (also labeled“(B)”) are configured by ATM management system commands. The leased lineparts represented by the dashed thick lines are configured by TN 1605commands. The leased line parts represented by the dashed thin lines(also labeled “(C) ” and “(D) ”) are configured by ATM management systemcommands. The parts labeled “(A)” and “(C)” pertain to intra-domainsegments while the parts labeled “(B)” and “(D)” pertain to inter-domainsegments. It should be noted that segments within the ATM network areconfigured by the ATM management system commands while segmentsextending beyond the ATM network are configured by TN 1605 commands inthe exemplary communication path configuring of the exemplary tri-levelnodal network 1900.

Referring now to FIGS. 20A and 20B, exemplary mapping embodiments in anexemplary tri-level nodal environment implementation in accordance withthe present invention are illustrated generally at 2000 and 2050,respectively. The exemplary mapping as illustrated at 2000 includes aman machine line (MML) handler 2005 and an ATM management system 2010that enable the general management of the illustrated tri-level nodalenvironment implementation. Specifically, the MML handler 2005 enablesthe configuring of the TN 1605 portion, and the ATM management system2010 enables the configuring of the ML 1620 and MG 1625 portions. Switchdevice management (SDM) parts 2015TN and 2015ML enable communicationbetween the TN 1605 and the ML 1620, along with the transport handler(TRH) 2020. In exemplary embodiment(s), a switch device (SD) maycorrespond to a logical device that terminates a 31 channel logical E1line. A context handler 2025 enables communication from/to the ML 1620to/from the ATM network.

In exemplary embodiment(s), an H.248 protocol may be employed forcommunication over the ATM network. A mapping part portion 2030 storesthe topology of one or more MGs 1625 as well as a protocol mapping ofthe SDM part(s) (e.g., of the circuit-switched address space) to theH.248 (e.g., of the packet-switched address space). The exemplarymapping as illustrated at 2050 includes indications of an add portinstruction 2055 and an add port response instruction 2060 exchangedbetween the TN 1605 and the ML 1620. These instructions, which mayoriginate at the MML terminal 2005, configure the mapping providing bythe H.248 table 2065 and the SD table 2075. The H.248 table 2065 and theSD table 2075 together provide a mapping between H.248 addresses (e.g.,an “MG/Subrack/Slot/Port” address) and SD addresses (e.g., and “SD1”address).

It should be noted that the H.248 addresses may have an unrestrictedand/or unstructured format that differs from and may be more flexiblethan the “MG/Subrack/Slot/Port” as illustrated in FIG. 20B. In fact, anoperator may be empowered to select such names. The MG 1625 includes anH.248 object table 2080, which may be configured at least in part by theATM management system 2010, for establishing communication paths throughthe MG 1625. The tri-level approach described hereinabove in variousembodiments enables pre-existing narrowband technology to be used withbroadband technology. Moreover, the tri-level approach multiplies theability to reuse a pre-existing narrowband switch by enabling a singlenarrowband switch to provide switching intelligence to multiplebroadband switches.

Referring now to FIG. 21, an exemplary tri-level nodal environment inaccordance with the present invention is illustrated generally at 2100.The exemplary tri-level nodal environment 2100 includes two or moretelecommunications nodes (TN) 2105 (e.g., which may correspond to, forexample, the PSTN/ISDN node 330 of FIG. 3 et seq., the call/connectioncontrol node 405 of FIG. 4 et seq. and/or the TN 1605 of FIG. 17 etseq.). All of the TNs 2105 are connected to one or more mediation logic(ML) nodes 2115 (e.g., which may correspond to, for example, the ML 1620of the embodiment(s) of FIG. 16 et seq.). The ML 2115 is controlled byall of the TNs 2105.

The ML 2115 is further connected to a broadband network (BN) 2125 (e.g.,which may correspond to, for example, the ATM network 215 of theembodiment(s) of FIG. 4 et seq.). The BN 2125 provides a medium for theML 2115 to be in communication with one or more media gateways (MGs)2120 (e.g., which may correspond to, for example, the MGs 1625 of theembodiment(s) of FIG. 16 et seq.). It should be understood that thearchitecture illustrated in the exemplary tri-level nodal environment2100 may be modified, rearranged, etc., especially in accordance withthe other illustrated and described embodiments and teachings from FIGS.15–15C, as well as those of FIGS. 16–20B. For example, the ML 2115 mayinclude a co-located MG 2120 for call connection between the TN 2105 andthe BN 2125.

Referring now to FIG. 22, to support multiple TNs 2105 connected to oneor more ML 2115, the transport handler (TRH) 2200 (e.g., which maycorrespond to, for example, the TRH 2020 of FIGS. 20A and 20B) withinthe ML 2115 and TNs 2105 is updated to provide an identifier 2250 witheach message 2220 sent between the TNs 2105 and the ML 2115. Messages2220 sent between the TNs 2105 and the ML 2115 are transported overEthernet control links utilizing the Internet Protocol (IP). Therefore,each message 2220 includes an IP address for the destination node (e.g.,which can be, for example, a control processor within the ML 2115). Thethird octet of the IP address uniquely identifies the switch (e.g., TN2105 or ML 2115) associated with the destination node.

The TRH 2250 in both the TN 2105 and the ML 2115 has access to the thirdoctet of the IP address for each message 2220, and therefore can prependthe source (message sending node) identifier 2250, along with thedestination (message receiving node) identifier (not shown) to themessage 2220. The destination identifier is retrieved from the thirdoctet of the IP address. By prepending the message 2220 with the sourceidentifier 2250 and destination identifier, the message 2220 parametersremain unchanged. However, the destination node must strip off theidentifiers 2250 before processing the message 2220. Therefore, in otherembodiments, the TRH 2200 can add an additional parameter to the message2220 that includes the source identifier 2250.

Referring now to FIGS. 23A and 23B, in addition to including at least asource identifier with each message (e.g., an AddPort message 2350 orAddPortRes message 2355) between the ML 2115 and the TNs 2105, themapping of switch device (SD) addresses 2320 (e.g., which may correspondto, for example, the switch device addresses within the SD table 2075 ofFIG. 20B) to MG port addresses 2310 (e.g., which may correspond to, forexample, the H.248 addresses within the H.248 table 2065 of FIG. 20B)must be extended to support more than one TN 2105. Therefore, uponreceipt of an AddPort message 2350 (e.g., which may correspond to, forexample, the add port instruction 2055 of FIG. 20B) that includes the TN(source) identifier, the ML 2115 stores the TN identifier 2250 againstthe assigned SD 2320 in the SD Table 2325. The TN identifier 2250 isalso used for processing other messages, such as an AuditPort message,where the TN identifier sent with the AuditPort message is checkedagainst the TN identifier 2250 stored with the SD 2320 associated withthe MG port 2310 to confirm that the requesting TN 2105 has theauthority to request an audit of that MG port 2310.

In exemplary embodiments, the SD address 2320 identifies a logicaldevice that terminates a 31 channel logical E1 line of the TN 2105. TheSD address 2320 (e.g., circuit switched address) is mapped to a BNaddress 2310 (e.g., packet-switched address) by associating the assignedSD address 2320 in the SD table 2325 with a MG port address 2310 in a BNtable 2305 (e.g., which may correspond to, for example, the H.248 table2065 of FIG. 20B). The MG port address 2310 represents the logical E1line of the TN 2105, and is associated with a real port of a MG in theBN.

As shown in FIG. 23B, in order to establish connections between TNs 2105sharing the same ML 2115, an address 2315 for a MG logical port (notshown) is stored in the BN table 2305. The MG logical port address 2315is associated with two real ports of one or more MG's in the BN. Inaddition, the MG logical port address 2315 represents a logical E1 pathbetween the two TNs 2105. For both TNs 2105 to own a particular logicalport, the TN identifier 2250 of both TNs 2105 is stored against theaddress 2320 of the SD associated with the logical port address 2315 inthe SD table 2325.

FIG. 24 illustrates an exemplary method in flowchart form for mappingbetween address spaces in the tri-level nodal environment of FIG. 21 inaccordance with the present invention. When a first telecommunicationsnode (TN1) sends an AddPort message for a particular logical port (LP1)to the ML (step 2400), the ML assigns LP1 to TN1 (step 2410) by storingthe identifier for TN1 against the SD associated with LP1. In response,the ML sends an AddPortRes message to TN1 (step 2420) that includes atleast the assigned SD address.

If a second telecommunications node (TN2) sends an AddPort message forLP1 to the ML (step 2430), the ML checks LP1 to ensure that two TNs arenot already assigned to LP1, and if not, the ML assigns LP1 to TN2 (step2440) by storing the identifier for TN2 against the SD associated withLP1. In response, the ML sends an AddPortRes message to TN2 (step 2450)including at least the assigned SD address. Before TN2 sends the AddPortmessage (step 2430), if TN1 sends a ReleasePort message to the ML (step2460), the ML releases LP1 (step 2470) by removing the identifierassociated with TN1 from the SD associated with LP1. It should be notedthat TN1 can send a ReleasePort message at any time, without affectingthe assignment of LP1 to TN2, and vice-versa.

FIG. 25 illustrates a further exemplary mapping embodiment in theexemplary tri-level nodal environment of FIG. 21 in accordance with thepresent invention. When an AddPort message 2350 is received specifying aparticular logical port (LP1), the switch device management (SDM) 2500(e.g., which may correspond to, for example, the SDM 2015 of FIG. 20A)within the ML 2115 assigns a particular call handler (CH) 2510 based onthe subrack value for LP1 included within the AddPort message 2350. Theslot and interface values for LP1 included within the AddPort message2350 are used by the SDM 2500 to determine LP1 2515. It should be notedthat both the slot and interface parameters have 100 possible valueseach, thus creating up to 10,000 unique logical ports 2515 per CH 2510.The SDM 2500 further selects a SD 2520 for LP1 2515 and passes the SDaddress and CH address back to the TN 2105 that sent the AddPort messagein the AddPortRes message 2355.

Referring now to FIG. 26, to establish a connection between two TNs 2105a and 2105 b sharing the same ML 2115, each TN 2105 a and 2105 b sends aseparate EstablishPath message 2600 a and 2600 b, respectively, to theML 2115. Each EstablishPath message 2600 a and 2600 b requests a logicalpath 2650 a and 2650 b, respectively, be setup between the logical port(LP1) 2515 owned by both TN 2105 a and TN 2105 b and a real port (RP1 orRP2) in the BN 2125. For example, the EstablishPath message 2600 a sentby TN 2105 a requests a logical path 2650 a from LP1 to RP1 associatedwith MG 2120 a, whereas the EstablishPath message 2600 b sent by TN 2105b requests a logical path 2650 b from LP1 to RP2 associated with MG 2120b.

Therefore, each TN 2105 a and 2105 b separately defines semi-permanentconnections 2650 a and 2650 b through the ML 2115. After bothsemi-permanent connections are defined, PVC connections 2650 a and 2650b can be established. Furthermore, after both logical paths 2650 a and2650 b are setup, the ML 2115 realizes that real ports (RP1 and RP2) areon the end points of the logical paths 2650 a and 2650 b and establishesa physical connection 2660 from RP1 to RP2 over the BN 2125, whilemaintaining the logical paths 2650 a and 2650 b involving LP1. Theresources used in LP1 2515 for the call connection are maintained untilthe connection is removed by a ReleasePath message (not shown).

FIG. 27 illustrates an exemplary method in flowchart form forestablishing a connection between two TNs sharing the same ML. When afirst telecommunications node (TN1) sends an EstablishPath message forLP1 and RP1 to the ML (step 2700), the ML establishes a logical pathbetween LP1 in the ML and RP1 in the BN (step 2710). Thereafter, if asecond telecommunications node (TN2) sends an EstablishPath message forLP1 and RP2 to the ML (step 2720), the ML establishes a logical pathbetween LP1 and RP2 (step 2730), and a physical connection between RP1and RP2 over the BN (step 2740).

However, if before TN2 sends the EstablishPath message (step 2720), TN1sends a ReleasePath message to the ML (step 2750), the ML releases thelogical path from LP1 to RP1 and releases resources reserved in LP1 forthe call (step 2770). In addition, if TN2 does not send theEstablishPath message to the ML (step 2720) before the expiration of apredefined time period (step 2760), the ML releases the logical pathfrom LP1 to RP1 and releases resources in LP1 reserved for the call(step 2770).

Although embodiment(s) of the methods, systems, and arrangements of thepresent invention have been illustrated in the accompanying Drawings anddescribed in the foregoing Detailed Description, it will be understoodthat the present invention is not limited to the embodiment(s)disclosed, but is capable of numerous rearrangements, modifications, andsubstitutions without departing from the spirit and scope of the presentinvention as set forth and defined by the following claims.

1. An interworking node operatively connectable to a plurality of callcontrol nodes each including switching intelligence and narrowbandswitching fabric and a plurality of connection control nodes eachincluding broadband switching fabric, said interworking node comprising:means for interworking between said plurality of call control nodes andsaid plurality of connection control nodes; means for receiving messagesfrom said plurality of call control nodes, each of said messagesincluding an identifier associated with one of said plurality of callcontrol nodes, each of said messages controlling said interworkingmeans; and a plurality of resources for interworking between saidplurality of call control nodes and said plurality of connection controlnodes, an assigned one of said plurality of resources having saididentifier of at least one of said call control nodes associatedtherewith wherein said assigned resource comprises a logical port forsupporting connections between two of said plurality of call controlnodes, said logical port having said identifier of said two call controlnodes associated therewith.
 2. The interworking node of claim 1, whereinsaid logical port represents a logical E1 path between said two callcontrol nodes.
 3. The interworking node of claim 2, wherein saidassigned resource further comprises a call handler within saidinterworking node, said logical port being handled by said call handler.4. The interworking node of claim 3, wherein said assigned resourcefurther comprises a switch device within said interworking node, saidswitch device being a logical device that corresponds to the logical E1path between said two call control nodes.
 5. The interworking node ofclaim 4, wherein said means for interworking further comprises: amapping function for mapping an address for said switch device to anaddress for said logical port.
 6. The interworking node of claim 1,wherein said means for interworking further comprises: means forestablishing logical paths between said logical port and real portsassociated with two of said plurality of connection control nodes. 7.The interworking node of claim 6, wherein said means for interworkingfurther comprises: means for establishing a physical connection betweensaid real ports of said two connection control nodes for a callconnection.
 8. A system for combining narrowband and broadband transportmechanisms in a communications network, comprising: a plurality of callcontrol nodes each including switching intelligence and narrowbandswitching fabric; a plurality of connection control nodes each includingbroadband switching fabric; at least one intermediate node operativelyconnectable to said plurality of call control nodes and said pluralityof connection control nodes, said at least one intermediate node beingadapted to interwork between said plurality of call control nodes andsaid plurality of connection control nodes, said at least oneintermediate node being controlled by all of said plurality of callcontrol nodes; wherein each said call control node of said plurality ofcall control nodes has an identity associated therewith, each said callcontrol node of said plurality of call control nodes including saidrespective identity with each message transmitted to said intermediatenode; and wherein said intermediate node has a plurality of resourcestherein for interworking between said plurality of call control nodesand said plurality of connection control nodes, an assigned one of saidplurality of resources having said identity of at least one of said callcontrol nodes associated therewith wherein said assigned resourcecomprises a logical port for supporting connections between two of saidplurality of call control nodes, said logical port having saididentifier of said two call control nodes associated therewith.
 9. Thesystem of claim 8, wherein said plurality of connection control nodescomprise at least part of a broadband network.
 10. The system of claim8, wherein said logical port represents a logical E1 path between saidtwo call control nodes.
 11. The system of claim 10, wherein saidassigned resource further comprises a call handler within saidintermediate node, said logical port being handled by said call handler.12. The system of claim 11, wherein said assigned resource furthercomprises a switch device within said intermediate node, said switchdevice being a logical device that corresponds to the logical E1 pathbetween said two call control nodes.
 13. The system of claim 12, whereinsaid intermediate node further comprises a mapping function for mappingan address for said switch device to an address for said logical port.14. The system of claim 10, wherein said intermediate node is furtheradapted to establish logical paths between said logical port and realports associated with two of said plurality of connection control nodes.15. The system of claim 14, wherein said intermediate node is furtheradapted to establish a physical connection between said real ports ofsaid two connection control nodes for a call connection.
 16. A methodfor combining narrowband and broadband transport mechanisms in acommunications network, comprising the steps of: providing a pluralityof call control nodes each including switching intelligence andnarrowband switching fabric; providing a plurality of connection controlnodes each including broadband switching fabric; interworking betweensaid plurality of call control nodes and said plurality of connectioncontrol nodes using at least one intermediate node, said at least oneintermediate node being controlled by all of said plurality of callcontrol nodes; wherein each said call control node of said plurality ofcall control nodes has an identity associated therewith, and furthercomprising the step of transmitting a message from a sending one of saidplurality of call control nodes, said message including said identity ofsaid sending call control node and wherein said intermediate node has aplurality of resources therein for interworking between said pluralityof call control nodes and said plurality of connection control nodes andfurther comprising the step of assigning said identity of at least oneof said plurality of call control nodes to an assigned one of saidplurality of resources wherein said assigned resource comprises alogical port for supporting connections between two of said plurality ofcall control nodes, and wherein said step of assigning further comprisesthe step of: assigning said identity of said two call control nodes tosaid logical port.
 17. The method of claim 16, wherein said assignedresource further comprises a call handler within said intermediate node,and further comprising the step of: handling said logical port by saidcall handler.
 18. The method of claim 17, wherein said assigned resourcefurther comprises a switch device within said intermediate nodecorresponding to a logical E1 path between said two call control nodes,and further comprising the step of: mapping between an address for saidswitch device and an address for said logical port.
 19. The method ofclaim 16, further comprising the step of: establishing logical pathsbetween said logical port and real ports associated with two of saidplurality of connection control nodes.
 20. The system of claim 19,further comprising the step of: establishing a physical connectionbetween said real ports of said two connection control nodes for a callconnection.
 21. A method for supporting control of at least oneintermediate node by a plurality of call control nodes in acommunications network, said plurality of call control nodes eachincluding switching intelligence and narrowband switching fabric, saidintermediate node interworking between said plurality of call controlnodes and a plurality of connection control nodes each having broadbandswitching fabric, said method comprising the steps of: providing eachsaid call control node of said plurality of call control nodes with anidentity; and assigning said identity of at least one of said pluralityof call control nodes to an assigned one of a plurality of resourceswithin said intermediate node, said plurality of resources forinterworking between said plurality of call control nodes and saidplurality of connection control nodes transmitting a message from asending one of said plurality of call control nodes, said messageincluding said identity of said sending call control node; wherein saidassigned resource comprises a logical port for supporting connectionsbetween two of said plurality of call control nodes, and wherein saidstep of assigning further comprises the step of: assigning said identityof said two call control nodes to said logical port.